diff --git a/build-project.sh b/build-project.sh
index 0f7c75e..98b90d6 100755
--- a/build-project.sh
+++ b/build-project.sh
@@ -1,15 +1,6 @@
-trap 'echo "Interrupted";  
-  rm main;
-  cp employeeLogin.c.bak employeeLogin.c;
-  cp mainMenu.c.bak mainMenu.c;
-  cp createEmployeeAccount.c.bak createEmployeeAccount.c;
-  rm employeeLogin.c.bak;
-  rm mainMenu.c.bak;
-  rm createEmployeeAccount.c.bak;
-  cd ..;
-  rm -r build; exit' SIGINT
 clear
 ceedling test:all 
+rm -r build/
 
 
 cd src/
@@ -20,36 +11,8 @@ mv temp.txt employeesCredentialsList.txt
 sed '/Name : John/,$d' employeesData.txt > temp.txt
 mv temp.txt employeesData.txt
 
-# backup files
-for file in employeeLogin.c mainMenu.c createEmployeeAccount.c; do
-  cp "$file" "$file.bak"
-done
-
-# replace .c with .h in respective files
-sed -i 's/createEmployeeAccount.c/createEmployeeAccount.h/g' mainMenu.c
-sed -i 's/showGeneralInfoEmployee.c/showGeneralInfoEmployee.h/g' employeeLogin.c
-sed -i 's/mainMenu.c/mainMenu.h/g' employeeLogin.c
-sed -i 's/employeeLogin.c/employeeLogin.h/g' createEmployeeAccount.c
-
-# remove 'src/'
-for file in employeeLogin.c createEmployeeAccount.c; do
-  sed -i 's/src\///g' "$file"
-done
-
-# compile and run program
-gcc main.c mainMenu.c employeeLogin.c showGeneralInfoEmployee.c createEmployeeAccount.c -o main
+gcc  mainMenu.c error.c createEmployeeAccount.c showGeneralInfoEmployee.c employeeLogin.c createCustomer.c helperFunctions.c loginCustomer.c customerMenu.c main.c  -o main
 ./main
 rm main
 
-# restore backups
-for file in employeeLogin.c mainMenu.c createEmployeeAccount.c; do
-  cp "$file.bak" "$file"
-done
-
-# remove backups
-for file in employeeLogin.c.bak mainMenu.c.bak createEmployeeAccount.c.bak; do
-  rm "$file"
-done
-
 cd ..
-rm -r build/
diff --git a/project.yml b/project.yml
index 640cb8f..b32843f 100644
--- a/project.yml
+++ b/project.yml
@@ -34,7 +34,14 @@
     - +:tests/**
     - -:tests/support
   :source:
-    - src/**
+    - src/createCustomer.*
+    - src/customerLogin.*
+    - src/helperFunctions.*  
+    - src/error.*
+    - src/createEmployeeAccount.*
+    - src/employeeLogin.*
+    - src/mainMenu.*
+    - src/showGeneralInfoEmployee.*
   :support:
     - tests/support
   :libraries: []
diff --git a/src/createCustomer.c b/src/createCustomer.c
new file mode 100644
index 0000000..9d3a93a
--- /dev/null
+++ b/src/createCustomer.c
@@ -0,0 +1,129 @@
+#include "createCustomer.h"
+/*Code written by Julius Philipp Engel, fdai7057*/
+int generateID()
+{
+	srand(clock());
+	const int MIN = 1000000, MAX = 9000001;
+	int pseudoRandomIDForCustomer = (rand() % MAX) + MIN;
+	return pseudoRandomIDForCustomer;
+}
+
+void collectCustomerProperties()
+{
+	customer_t instance;
+	instance.forename = calloc(15+1,sizeof(char));
+	instance.surname = calloc(15+1,sizeof(char));
+	instance.password = calloc(20+1,sizeof(char));
+	instance.ID = generateID();
+	int letterCounter = 0;
+	int letterMaximum = 15;
+	int errorResult = 0;
+	char userInput=' ';
+	bool inputTooLong = false, foundComma = false;
+	printf("To create a new user, enter the information required below.\n");
+	printf("Enter forename (max. 15 letters):\n");
+	while(letterCounter<letterMaximum && (userInput=getchar())!='\n'){
+		*(instance.forename+letterCounter) = userInput;
+		++letterCounter;
+		if(letterCounter>=letterMaximum){
+			inputTooLong = true;	
+			break;
+		}
+	}
+	if(inputTooLong){
+		errorResult = errorMessage(-7);
+		if(errorResult==-7) exit(-1);
+	}
+	else{
+	*(instance.forename+letterCounter) = '\0';
+	letterCounter = 0;
+	}
+	if(!isLetterOfAlphabet(instance.forename)){
+		errorResult = errorMessage(-10);
+		exit(-1);
+	}
+	printf("Enter surname (max. 15 letters):\n");
+	while(letterCounter<letterMaximum && (userInput=getchar())!='\n'){
+		*(instance.surname+letterCounter) = userInput;
+		++letterCounter;
+		if(letterCounter>=letterMaximum){
+			inputTooLong = true;
+			break;
+		}
+	}
+	if(inputTooLong){
+		errorResult = errorMessage(-8);
+		if(errorResult==-8) exit(-1);
+	}else{
+	*(instance.surname+letterCounter) = '\0';
+	letterCounter = 0;
+	}
+	if(!isLetterOfAlphabet(instance.surname)){
+		errorResult = errorMessage(-11);
+		if(errorResult==-11) exit(-1);
+	}
+	printf("Enter password (max. 20 letters):\n");
+	letterMaximum = 20;
+	while(letterCounter<letterMaximum && (userInput=getchar())!='\n'){
+		*(instance.password+letterCounter) = userInput;
+		++letterCounter;
+		if(letterCounter>=letterMaximum){
+			inputTooLong = true;
+			break;
+		}
+	}
+	if(inputTooLong){
+		errorResult=errorMessage(-9);
+		if(errorResult==-9) exit(-1);
+	}else{
+	*(instance.password+letterCounter) = '\0';
+	}
+	
+	letterCounter = 0;
+	printf("Enter balance (max. 10 digits):\n");
+	char *balanceCharacters = calloc(10+1+1+1,sizeof(char));
+	letterMaximum = 10;
+	while(letterCounter<=letterMaximum && (userInput=getchar())!='\n'){
+		*(balanceCharacters+letterCounter) = userInput;
+		++letterCounter;
+		if(letterCounter>letterMaximum){
+			inputTooLong = true;
+			break;
+		}
+	}
+	if(inputTooLong){
+		errorResult = errorMessage(-12);
+		if(errorResult==-12) exit(-1);
+	}else{
+		if(!foundComma){
+			*(balanceCharacters+letterCounter) = '.';
+		       ++letterCounter;
+	       		*(balanceCharacters+letterCounter) = '0';
+	 		++letterCounter;		
+		}
+	*(balanceCharacters+letterCounter) = '\0';
+	}
+	if(!everyCharacterIsDigit(balanceCharacters)){
+		puts("You have entered a character that is not a number. This is not allowed. Aborting!");
+		exit(-1);
+	  }
+	instance.balance = balanceToDouble(balanceCharacters);
+	printf("Account successfully created. Your ID is: %d. Note it somewhere!\n",instance.ID);
+	customer_t *referenceToCustomerInstance = &instance;
+	writeCustomerPropertiesToFile(referenceToCustomerInstance);
+}
+
+void writeCustomerPropertiesToFile(customer_t *referenceToCustomerInstance)
+{
+	FILE *customerData = fopen("CustomerData.txt","a");
+	int errorResult = 0;
+	if(customerData!=NULL){
+fprintf(customerData,"%s\nID=%d\nForename=%s\nSurname=%s\nPassword=%s\nBalance=%.4f€\n\n",
+generateCheckString(referenceToCustomerInstance->ID, referenceToCustomerInstance->password),referenceToCustomerInstance->ID,referenceToCustomerInstance->forename,referenceToCustomerInstance->surname,referenceToCustomerInstance->password, referenceToCustomerInstance->balance);
+	fclose(customerData);
+	}
+	else{
+		errorResult = errorMessage(-6);
+		if(errorResult==-6) exit(-1);
+	}
+}
diff --git a/src/createCustomer.h b/src/createCustomer.h
new file mode 100644
index 0000000..1b87870
--- /dev/null
+++ b/src/createCustomer.h
@@ -0,0 +1,13 @@
+#ifndef CREATE_CUSTOMER_H
+#define CREATE_CUSTOMER_H
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <time.h>
+#include "customerProperties.h"
+#include "helperFunctions.h"
+#include "error.h"
+int generateID();
+void collectCustomerProperties();
+void writeCustomerPropertiesToFile(customer_t *);
+#endif
diff --git a/src/createEmployeeAccount.c b/src/createEmployeeAccount.c
index 10b8339..ac429e6 100644
--- a/src/createEmployeeAccount.c
+++ b/src/createEmployeeAccount.c
@@ -1,4 +1,3 @@
-#include "employeeLogin.c"
 
 #include "createEmployeeAccount.h"
 
diff --git a/src/customerMenu.c b/src/customerMenu.c
new file mode 100644
index 0000000..b3bb522
--- /dev/null
+++ b/src/customerMenu.c
@@ -0,0 +1,72 @@
+#include "customerMenu.h"
+
+int customerChoiceForMenuItem(int numberOfMenuItem)
+{
+	int returnStatus = 0;
+	switch(numberOfMenuItem){
+		case 1:
+			puts("You have chosen to send money.\n");
+			returnStatus = 1;
+			//call sendMoney();
+			break;
+		case 2:
+			puts("You have chosen to withdraw money.\n");
+			returnStatus = 2;
+			//call withDrawMoney();
+			break;
+		case 3:
+			puts("You have chosen to deposit money.\n");
+			returnStatus = 3;
+			//call depositMoney();
+			break;
+		case 4:
+			puts("You have chosen to request a loan.\n");
+			returnStatus = 4;
+			//call requestLoan();
+			break;
+		default:
+			puts("Invalid input.");
+			returnStatus = -1;
+	}
+	return returnStatus;
+}
+
+void showAllMenuEntries()
+{
+	
+	int userDecision = 0;
+
+	puts("\n\n");
+	puts("CUSTOMER MENU");
+	
+	puts("\n");
+	puts("Select between (1-4):");
+	puts("\n\n\n");
+
+	puts("->->->1. send money<-<-<-");
+	puts("\n\n\n");
+
+	puts("->->->2. withdraw money<-<-<-");
+	puts("\n\n\n");
+	
+	puts("->->->3. deposit money<-<-<-");
+	puts("\n\n\n");
+
+	puts("->->->4. request loan<-<-<-");
+	puts("\n\n\n");
+	
+	puts("Your decision: ");
+	scanf("%d",&userDecision);
+	customerChoiceForMenuItem(userDecision);
+}
+
+void menu(customer_t *c)
+{
+	if(c==NULL){
+		puts("Invalid pointer. Aborting!");
+		exit(-1);
+	}else{
+	puts("Welcome!");
+	showAllMenuEntries();	
+	}
+}
diff --git a/src/customerMenu.h b/src/customerMenu.h
new file mode 100644
index 0000000..4b51d22
--- /dev/null
+++ b/src/customerMenu.h
@@ -0,0 +1,6 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "customerProperties.h"
+int customerChoiceForMenuItem(int);
+void showAllMenuEntries();
+void menu(customer_t *);
diff --git a/src/customerProperties.h b/src/customerProperties.h
new file mode 100644
index 0000000..39661d1
--- /dev/null
+++ b/src/customerProperties.h
@@ -0,0 +1,11 @@
+#ifndef CUSTOMER_PROPERTIES_H
+#define CUSTOMER_PROPERTIES_H
+typedef struct Customer
+{
+	unsigned int ID;
+	char *IDAsString;
+	char *password;
+	char *forename, *surname;
+	double balance;	
+}customer_t;
+#endif
diff --git a/src/docs.txt b/src/docs.txt
new file mode 100644
index 0000000..c76de12
--- /dev/null
+++ b/src/docs.txt
@@ -0,0 +1,14 @@
+char *stringConcatenation(char string_1*, char string_2*):
+
+This function takes two char pointers. In this function a new string is created. This new string is the concatenation of string_1 and string_2. The size of the new string is the length of string_1 plus the length of string_2 plus one for '\0'. This function is needed when creating an unique check string for a customer.
+
+char *to_string(int number):
+
+This function takes an integer variable as its argument. It returns an string that contains the digits of number. For example to_string(176) would return "176\0". This function is needed to write data in form of characters into the customer file. 
+
+
+char *generateCheckString(int customerID, char *password): 
+
+The purpose of this function is to generate a string that is needed when a user wants to login. This string is searched for in the customer-data file and if it is found, the login is successful. This function is needed when a new user is created because then it is written in the file for the first time. 
+The format of the returned string is [ID]=[PASSWORD]. 
+For example generateCheckString(177,"tree") would return "177=tree\0".
diff --git a/src/employeeLogin.c b/src/employeeLogin.c
index 5bcded0..7c58fcf 100644
--- a/src/employeeLogin.c
+++ b/src/employeeLogin.c
@@ -1,6 +1,6 @@
-#include "mainMenu.h"
 #include "employeeLogin.h"
-#include "showGeneralInfoEmployee.c"
+//#include "createEmployeeAccount.h"
+#include "showGeneralInfoEmployee.h"
 
 
 bool employeesAccess(char* employeesAccessCode)
@@ -16,7 +16,7 @@ int checkEmployeeCredentials(char *inputUsername, char *inputPassword)
     char* listUsername = malloc(credentialLength * sizeof(char*));
     char* listPassword = malloc(credentialLength * sizeof(char*));
 
-    FILE* employeeList = fopen("src/employeesCredentialsList.txt","r");
+    FILE* employeeList = fopen("employeesCredentialsList.txt","r");
 
     if(employeeList == NULL )
     {
diff --git a/src/employeesCredentialsList.txt b/src/employeesCredentialsList.txt
index ed5a12d..3f2c0bf 100644
--- a/src/employeesCredentialsList.txt
+++ b/src/employeesCredentialsList.txt
@@ -9,3 +9,33 @@ Julius Insertcatfdai7057
 Mohamed MDfdai6618
 
 Shivam Schivam007fdlt3781
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/src/employeesData.txt b/src/employeesData.txt
index 16f8e9a..cf51135 100644
--- a/src/employeesData.txt
+++ b/src/employeesData.txt
@@ -32,3 +32,63 @@ Name : Shivam
 Last name : Chaudhary
 Adress : Fulda,leipzigerstrasse,6
 Phone number : +4918756871384 
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/src/error.c b/src/error.c
new file mode 100644
index 0000000..481d268
--- /dev/null
+++ b/src/error.c
@@ -0,0 +1,59 @@
+#include "error.h"
+
+int errorMessage(int errorCode)
+{
+	int returnValue=0;
+	switch(errorCode){
+	case -1:
+		puts("Login not successful.");
+		returnValue = -1;
+		break;
+	case -2:
+		puts("Maximum number of attempts reached.");
+		returnValue = -2;
+		break;
+	case -3:
+		puts("No menu entry available for this number.");
+		returnValue = -3;
+		break;
+	case -4:
+		puts("CustomerData.* not found. Make sure that you've created an user account before logging in for the first time. Without users there is no file. Aborting!");
+		returnValue = -4;
+		break;
+	case -5:
+		puts("You should be at least 18 years old to create a bank account!");
+		returnValue = -5;
+		break;
+	case -6:
+		puts("Error when trying to open a file to create a customer account.");
+		returnValue = -6;
+		break;
+	case -7:
+		puts("Forename too long. (length > 15 characters) Aborting!");
+		returnValue = -7;
+		break;
+	case -8:
+		puts("Surname too long. (length > 15 characters) Aborting!");
+		returnValue = -8;
+		break;
+	case -9:
+		puts("Password too long. (length > 20 characters) Aboring!");
+		returnValue = -9;
+		break;
+	case -10:
+		puts("You have entered an invalid character [ä,ö,ü, special characters] for your forename. This is not allowed. Aborting!");
+		returnValue = -10;
+		break;
+	case -11:
+		puts("You have entered an invalid character [ä,ö,ü, special characters] for your surname. This is not allowed. Aborting!");
+		returnValue = -11;
+		break;
+	case -12:
+		puts("You entered too many digits.");
+		returnValue = -12;
+		break;
+	default:
+		puts("Error code unknown.");
+	}
+	return returnValue;
+}
diff --git a/src/error.h b/src/error.h
new file mode 100644
index 0000000..867964a
--- /dev/null
+++ b/src/error.h
@@ -0,0 +1,3 @@
+#include <stdio.h>
+#include <stdlib.h>
+int errorMessage(int);
diff --git a/src/helperFunctions.c b/src/helperFunctions.c
new file mode 100644
index 0000000..2f61921
--- /dev/null
+++ b/src/helperFunctions.c
@@ -0,0 +1,151 @@
+#include "helperFunctions.h"
+/*Code written by Julius Philipp Engel, fdai7057*/
+
+char *stringConcatenation(char *string_1, char *string_2)
+{
+	int lengthStringOne = strlen(string_1);
+	int lengthStringTwo = strlen(string_2);
+	
+	if(lengthStringOne==0||lengthStringTwo==0){
+		printf("Empty strings are not allowed. Aborting.\n");
+		exit(-1);
+		//call error();
+	}
+	
+	const int totalLength = lengthStringOne + lengthStringTwo + 1;
+	char *result = calloc(totalLength, sizeof(char));
+	int i,j;
+	for(i=0,j=0;i<totalLength;++i){
+		if(i<lengthStringOne){
+			*(result+i) = *(string_1+i);
+		}else{
+			*(result+i) = *(string_2+j);
+			++j;
+		}
+	}
+	*(result+i) = '\0';
+	return result;
+}
+
+
+char *to_string(int number)
+{
+	if(number==0)
+	{
+		char *str = calloc(2,sizeof(char));
+		*(str) = '0';
+		*(str+1) = '\0';
+		return str;
+	}
+	else
+	{
+		int cpy = number, len = 0;
+		while(number>0){
+		++len;
+		number /= 10;
+		}
+		char *str = calloc(len+1, sizeof(char));
+		for(int i=0,j=len-1;i<len;++i,--j){
+		*(str+j) = '0' + (cpy % 10);
+		cpy /= 10;
+	}
+	*(str+len) = '\0';
+	return str;
+	}
+}
+
+unsigned int power(unsigned int base, unsigned int exponent){
+	if(base==0&&exponent==0) return 0;
+	else if(base>=1&&exponent==0) return 1;
+	else{
+	unsigned int result = 1, counter = 0;
+	while(counter<exponent){
+		result *= base;
+		++counter;
+	}
+	return result;
+	}
+}
+
+bool everyCharacterIsDigit(char *string)
+{
+	bool onlyDigits = true;
+	for(int i=0;*(string+i)!='\0';++i){
+		if( !(*(string+i)>='0'&&*(string+i)<='9') && *(string+i)!='.'){
+			onlyDigits = false;
+			break;
+		}
+	}
+	return onlyDigits;
+}
+
+bool isLetterOfAlphabet(char *string){
+	bool everyCharIsInAlphabet = true;
+	for(int i=0;*(string+i)!='\0';++i){
+		if(!(*(string+i)>='A'&&*(string+i)<='Z') && !(*(string+i)>='a'&&*(string+i)<='z')){
+			everyCharIsInAlphabet = false;
+			break;
+		}
+	}
+	return everyCharIsInAlphabet;	
+}
+
+unsigned int toUnsignedInteger(char *ID)
+{
+	if(everyCharacterIsDigit(ID)){
+	unsigned int result = 0;
+	int IDLength = strlen(ID);
+	for(int i=0, j = IDLength - 1;i<IDLength;++i,--j){
+		result += (*(ID+j) - '0') * power(10,i);
+	}
+		return result;
+	} else {
+		return 0;
+	}
+}
+
+char *generateCheckString(unsigned int customerID, char *customerPassword)
+{
+	char *IDString = to_string(customerID);
+	int IDLength = strlen(IDString);
+	int passwordLength = strlen(customerPassword);
+	int checkStringLength = IDLength + 1 + passwordLength + 1;
+	char *checkString = calloc(checkStringLength, sizeof(char));
+	checkString = strcat(IDString, "=");
+	checkString = strcat(checkString, customerPassword);
+	*(checkString+checkStringLength) = '\0';
+	return checkString;
+}
+
+double balanceToDouble(char *balanceAsString)
+{
+	double result, power;
+	int i=0, sign;
+	sign = (*(balanceAsString) == '-') ? -1 : 1;
+	if(*(balanceAsString)=='+'||*(balanceAsString)=='-'){
+		++i;
+	}
+	for(result = 0.0; *(balanceAsString+i)!='.';++i){
+		result = 10.0 * result + (*(balanceAsString+i) - '0');
+	}
+	if(*(balanceAsString+i)=='.'){
+		++i;
+	}
+	for(power = 1.0;*(balanceAsString+i)!='\0';++i){
+		result = 10.0 * result + (*(balanceAsString+i)- '0');
+		power *= 10.0;
+	}
+	return sign * result / power;
+}
+
+unsigned int calculateStringLength(char *string){
+	int length = 0;
+	while(*(string+length)!='\0') ++length;
+	return length;
+}
+
+bool characterIsUpperCase(char inputCharacter)
+{
+	bool result = (inputCharacter>='A'&&inputCharacter<='Z') ? true : false;
+	return result;
+}
diff --git a/src/helperFunctions.h b/src/helperFunctions.h
new file mode 100644
index 0000000..a650e74
--- /dev/null
+++ b/src/helperFunctions.h
@@ -0,0 +1,18 @@
+#ifndef STRING_MANIPULATION_H
+#define STRING_MANIPULATION_H
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdbool.h>
+#define UNITY_INCLUDE_CONFIG_H
+char *stringConcatenation(char *, char *);
+char *to_string(int);
+char *generateCheckString(unsigned int, char *);
+unsigned int toUnsignedInteger(char *);
+unsigned int power(unsigned int, unsigned int);
+bool everyCharacterIsDigit(char *);
+bool isLetterOfAlphabet(char *);
+double balanceToDouble(char *);
+unsigned int calculateStringLength(char *);
+bool charIsUpperCase(char );
+#endif
diff --git a/src/loginCustomer.c b/src/loginCustomer.c
new file mode 100644
index 0000000..f466181
--- /dev/null
+++ b/src/loginCustomer.c
@@ -0,0 +1,87 @@
+#include "loginCustomer.h"
+
+bool checkLogin(bool loginSuccessful)
+{	
+	return (loginSuccessful) ? true : false;
+}
+
+void collectCustomerDataForLogin(int attempts)
+{
+	customer_t c;
+	c.IDAsString = calloc(15+1, sizeof(char));
+	c.password = calloc(20+1, sizeof(char));
+	int digitCharacterFromUser, passwordCharacterFromUser;
+	int IDLengthCounter = 0, passwordLengthCounter = 0;
+	int errorResult = 0;
+	const int IDMaxLength = 16, passwordMaxLength = 21;
+	printf("Enter ID:\n");
+	while((digitCharacterFromUser=getchar())!='\n'&&IDLengthCounter<IDMaxLength){
+			if(digitCharacterFromUser>='0'&&digitCharacterFromUser<='9'){
+				*(c.IDAsString+IDLengthCounter) = digitCharacterFromUser;
+			}
+			else{
+				printf("Character entered is not a digit. Aborting.\n");
+				exit(-1);
+			}
+		++IDLengthCounter;	
+	}
+	*(c.IDAsString+IDLengthCounter) = '\0';
+	if(IDLengthCounter>=IDMaxLength){
+		printf("ID entered is too long. Aborting.\n");
+		exit(-1);
+	}
+	printf("Enter password:\n");
+	while((passwordCharacterFromUser=getchar())!='\n'&&passwordLengthCounter<passwordMaxLength){
+		*(c.password+passwordLengthCounter) = passwordCharacterFromUser;
+		++passwordLengthCounter;
+	}
+	*(c.password+passwordLengthCounter) = '\0';
+	
+	if(passwordLengthCounter>=passwordMaxLength){
+		printf("Password entered is too long. Aborting.\n");
+		exit(-1);
+	}
+	bool loginSuccessful = loginCustomer(&c);
+		free(c.IDAsString);
+		free(c.password);
+	if(loginSuccessful) {
+		//call menu();
+		menu(&c);
+	}else if(!loginSuccessful && attempts < MAX_LOGIN_ATTEMPTS){
+		printf("You have %d attempts left.\n", MAX_LOGIN_ATTEMPTS - attempts);
+		collectCustomerDataForLogin(++attempts);
+	}else{
+		errorResult = errorMessage(-2);
+		if(errorResult==-2) exit(-1);
+	}	
+}
+
+bool loginCustomer(customer_t *c)
+{
+	bool foundCustomerEntryInFile = false;
+	unsigned int IDAsNumber = toUnsignedInteger(c->IDAsString); 
+	char *searchForThisString = generateCheckString(IDAsNumber,c->password);
+	char *lineFromCustomerFile = calloc(40,sizeof(char));
+	int errorResult = 0;
+	FILE *readCustomerFile = fopen("CustomerData.txt", "r");
+	if(readCustomerFile==NULL){
+		errorResult = errorMessage(-4);
+		if(errorResult==-4) exit(-1);
+	}
+	while((fscanf(readCustomerFile,"%s",lineFromCustomerFile)!=EOF)){
+			if(strcmp(searchForThisString,lineFromCustomerFile)==0){
+				foundCustomerEntryInFile = true;
+				break;
+			}
+	}
+	free(lineFromCustomerFile);
+	if(checkLogin(foundCustomerEntryInFile)){
+		printf("Login successful.\n");
+		fclose(readCustomerFile);
+		return foundCustomerEntryInFile;
+	}else{
+		errorResult = errorMessage(-1);
+	}
+	fclose(readCustomerFile);
+	return foundCustomerEntryInFile;
+}
diff --git a/src/loginCustomer.h b/src/loginCustomer.h
new file mode 100644
index 0000000..e126f86
--- /dev/null
+++ b/src/loginCustomer.h
@@ -0,0 +1,14 @@
+#ifndef LOGIN_CUSTOMER_H
+#define LOGIN_CUSTOMER_H
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include "createCustomer.h"
+#include "customerMenu.h"
+#include "error.h"
+#define MAX_LOGIN_ATTEMPTS 3
+bool checkLogin(bool);
+void collectCustomerDataForLogin(int);
+bool loginCustomer(customer_t *);
+#endif
diff --git a/src/main b/src/main
new file mode 100755
index 0000000..dae05f4
Binary files /dev/null and b/src/main differ
diff --git a/src/main.c b/src/main.c
index 48041ae..f13161e 100644
--- a/src/main.c
+++ b/src/main.c
@@ -2,10 +2,12 @@
 #include "employeeLogin.h"
 #include"showGeneralInfoEmployee.h"
 
-int main()
+void runBankManagementSystem()
 {
-
-    ageInput();
-    
-    return 0;
+	ageInput();
 }
+
+int main()
+{
+	runBankManagementSystem();
+}
\ No newline at end of file
diff --git a/src/mainMenu.c b/src/mainMenu.c
index 8fcb882..e1a16f8 100644
--- a/src/mainMenu.c
+++ b/src/mainMenu.c
@@ -1,6 +1,9 @@
 #include "mainMenu.h"
 #include "employeeLogin.h"
-#include "createEmployeeAccount.c"
+#include "createEmployeeAccount.h"
+#include "createCustomer.h"
+#include "error.h"
+#include "showGeneralInfoEmployee.h"
 
 
 
@@ -36,13 +39,14 @@ void ageInput()
 
     char* userInput = malloc(20*sizeof(char*));
     char* userInputPointer;
-
+    int input, ctr=0;
     long age;
-
     printf("\nPlease specify your age : ");
-    scanf("%s",userInput);
-
-
+    while((input=getchar())!='\n'){
+	*(userInput+ctr) = input;
+    	++ctr;
+    }
+    	*(userInput+ctr) = '\0';
     while (true)
     {
 	    /*the userInput string is changed to a number with the strtol function*/
@@ -50,7 +54,7 @@ void ageInput()
 	    age = strtol(userInput,&userInputPointer,10);
 
         if((checkIfInteger(userInput))&& (agePermission(age)))
-	    {
+	{
 
 	        printf("Access granted!\n\n\n\n");
 
@@ -64,9 +68,7 @@ void ageInput()
 
 	    else if((checkIfInteger(userInput)) && !(agePermission(age))) 
 	    {
-
-            printf("You should be at least 18 years old to create a bank account!\n");
-
+            errorMessage(-5);
 	        break;
 
 	    }
@@ -87,32 +89,40 @@ void menuInput()
 {
     char choiceInput[20];
     char* choiceInputPointer;
-    int selection;
+    int selection, input, ctr = 0;
     
-    scanf("%s", choiceInput);
-    selection = strtol(choiceInput, &choiceInputPointer, 10);
+    while((input=getchar())!='\n'){
+		choiceInput[ctr] = input;
+		++ctr;
+    }
+    choiceInput[ctr] = '\0';
+
+    selection = strtol(choiceInput, &choiceInputPointer, 10);	    
     
     while (!checkIfInteger(choiceInput) || !chooseOption(selection)) 
     {
         printf("Input invalid! try again!\n");
-
-        scanf("%s", choiceInput);
-        
-        selection = strtol(choiceInput, &choiceInputPointer, 10);
+	    ctr = 0;
+	    while((input=getchar())!='\n'){
+	        choiceInput[ctr] = input;
+		    ++ctr;
+	    }
+        choiceInput[ctr] = '\0';
+	    selection = strtol(choiceInput, &choiceInputPointer, 10);
     }
-    
     switch(selection) 
     {
-        case 1 : printf("\nLoginAsCostumer() function will be implemented here soon\n\n");
+        case 1 : collectCustomerDataForLogin(0);
                  break;
 
-        case 2 : printf("\ncreateCostumerAccount() function will be implemented here soon\n\n"); 
+        case 2 : collectCustomerProperties();
                  break;
 
         case 3 : getEmployeeAccessCode();
                  break;
 
-        case 4 : getNewEmployeeCredentials();
+        case 4 : getNewEmployeeCredentials(); 
+                 printf("\nsee you next time !\n\n"); 
                  break;
 
         case 5 : printf("\e[1;1H\e[2J"); 
@@ -137,6 +147,3 @@ void showMenu()
 }
 
 
-
-
-
diff --git a/src/mainMenu.h b/src/mainMenu.h
index 17d81bc..1fd5011 100644
--- a/src/mainMenu.h
+++ b/src/mainMenu.h
@@ -5,6 +5,7 @@
 #include<stdlib.h>
 #include<stdbool.h>
 #include<string.h>
+#include "loginCustomer.h"
 
 #define credentialLength 20
 
@@ -13,6 +14,7 @@ bool checkIfInteger(char* userInput);
 bool chooseOption(int choiceInput);
 
 void ageInput();
+void menuInput();
 void showMenu();
 void menuInput();
 
diff --git a/tests/test_CreateCustomer.c b/tests/test_CreateCustomer.c
new file mode 100644
index 0000000..4b48a74
--- /dev/null
+++ b/tests/test_CreateCustomer.c
@@ -0,0 +1,29 @@
+#include <unity.h>
+#include <limits.h>
+#include <math.h>
+#include "../src/helperFunctions.c"
+#include "../src/error.c"
+#include "../src/createCustomer.c"
+
+void setUp(){}
+void tearDown(){}
+
+void test_generateID(){
+	
+	const int test_values = USHRT_MAX;
+	
+	/*initialize blocks by calling generateID()*/
+	int *numbers = calloc(test_values, sizeof(int));	
+	for(int i=0;i<test_values;++i)
+	{
+		*(numbers+i) = generateID();
+		 //printf("%d\n", *(numbers+i));
+	}
+
+	/*assertions, range checking*/
+	int delta = 5000000, expected = 5000000;
+	for(int i=0;i<test_values;++i) 
+	{
+		TEST_ASSERT_INT_WITHIN(delta, expected,*(numbers+i));
+	}
+}
diff --git a/tests/test_CustomerMenu.c b/tests/test_CustomerMenu.c
new file mode 100644
index 0000000..4ba1f23
--- /dev/null
+++ b/tests/test_CustomerMenu.c
@@ -0,0 +1,24 @@
+#include <unity.h>
+#include "../src/customerMenu.c"
+
+void test_customerChoiceForMenuEntry()
+{
+	int decision = 1;
+	/*customer choses to send money, return 1*/
+	TEST_ASSERT_EQUAL_INT(1, customerChoiceForMenuItem(decision));
+	/*customer choses to withdraw money, return 2*/
+	decision = 2;
+	TEST_ASSERT_EQUAL_INT(2, customerChoiceForMenuItem(decision));
+	/*customer choses to deposit money, return 3*/
+	decision = 3;
+	TEST_ASSERT_EQUAL_INT(3, customerChoiceForMenuItem(decision));
+	/*customer choses to request a loan, return 4*/
+	decision = 4;
+	TEST_ASSERT_EQUAL_INT(4, customerChoiceForMenuItem(decision));
+	/*invalid input values, the return value should always be -1*/
+	int arrayOfInvalidValues[] = {-1,-2,-3,-4,-5,-6,-7,-8,-9,-10,-11,-12,-13,-14,-15,-16,-17,-18,-19,-20,0, 123,3247,6839,38593,3033,55055};
+	int length = sizeof(arrayOfInvalidValues)/sizeof(int);
+	for(int i=0;i<length;++i){
+			TEST_ASSERT_EQUAL_INT(-1, customerChoiceForMenuItem(arrayOfInvalidValues[i]));
+	}
+}
diff --git a/tests/test_Error.c b/tests/test_Error.c
new file mode 100644
index 0000000..036ac24
--- /dev/null
+++ b/tests/test_Error.c
@@ -0,0 +1,81 @@
+#include <unity.h>
+#include <time.h>
+#include <stdlib.h>
+#include "../src/error.c"
+
+void setUp(){}
+void tearDown(){}
+
+
+void test_error()
+{
+	/*arrange*/
+	srand(time(0));
+	int bound = 1000;
+	int invalidErrorCodes_1[bound];
+	int invalidErrorCodesLarge_2[bound];
+	int invalidErrorCodesLargest_3[bound];
+	
+	int validErrorCodeUnsuccessfulLogin[bound];
+	int validErrorCodeMaximumNumberOfAttempts[bound];
+	int validErrorCodeNoMenuEntryForNumber[bound];
+	/*new test cases*/
+	int validErrorCodeNoCustomerDataFile[bound];
+	int validErrorCodeTooYoung[bound];
+	int validErrorCodeCreatingFile[bound];
+	int validErrorCodeForenameTooLong[bound];
+	int validErrorCodeSurnameTooLong[bound];
+	int validErrorCodePasswordTooLong[bound];
+	
+	int validErrorCodeInvalidCharacterForename[bound];
+	int validErrorCodeInvalidCharacterSurname[bound];
+	int validErrorCodeTooManyDigits[bound];
+	
+
+	for(int i=0;i<bound;++i){
+		/*1000 numbers in the range from 1 to 2000 */
+		invalidErrorCodes_1[i] = rand() % 2000 + 1;
+		/*1000 numbers in the range from 1000.000 to 100.999.999*/
+		invalidErrorCodesLarge_2[i] = (rand() % 100000000) + 1000000;
+		/*1000 numbers in the range from 1.000.000.000 to 2.000.000.000*/
+		invalidErrorCodesLargest_3[i] = (rand() % 1000000001) + 1000000000 ;
+		/*1000 times -1 in array*/
+		validErrorCodeUnsuccessfulLogin[i] = -1;
+		/*1000 times -2 in array*/
+		validErrorCodeMaximumNumberOfAttempts[i] = -2;
+		/*1000 times -3 in array*/
+		validErrorCodeNoMenuEntryForNumber[i] = -3;
+		validErrorCodeNoCustomerDataFile[i] = -4;
+		validErrorCodeTooYoung[i] = -5;
+		validErrorCodeCreatingFile[i] = -6;
+		validErrorCodeForenameTooLong[i] = -7;
+		validErrorCodeSurnameTooLong[i] = -8;
+		validErrorCodePasswordTooLong[i] = -9;
+		validErrorCodeInvalidCharacterForename[i] = -10;
+		validErrorCodeInvalidCharacterSurname[i] = -11;
+		validErrorCodeTooManyDigits[i] = -12;
+}
+
+	/*act and assertions for invalid error codes*/
+	for(int i=0;i<bound;++i){
+		TEST_ASSERT_EQUAL_INT(0,errorMessage(invalidErrorCodes_1[i]));
+		TEST_ASSERT_EQUAL_INT(0,errorMessage(invalidErrorCodesLarge_2[i]));
+		TEST_ASSERT_EQUAL_INT(0,errorMessage(invalidErrorCodesLargest_3[i]));
+	}
+	/*act and assertions for valid error codes*/
+	for(int i=0;i<bound;++i){
+		TEST_ASSERT_EQUAL_INT(-1, errorMessage(validErrorCodeUnsuccessfulLogin[i]));
+		TEST_ASSERT_EQUAL_INT(-2, errorMessage(validErrorCodeMaximumNumberOfAttempts[i]));
+		TEST_ASSERT_EQUAL_INT(-3, errorMessage(validErrorCodeNoMenuEntryForNumber[i]));
+		/*new test cases*/
+		TEST_ASSERT_EQUAL_INT(-4, errorMessage(validErrorCodeNoCustomerDataFile[i]));
+		TEST_ASSERT_EQUAL_INT(-5, errorMessage(validErrorCodeTooYoung[i]));
+		TEST_ASSERT_EQUAL_INT(-6, errorMessage(validErrorCodeCreatingFile[i]));
+		TEST_ASSERT_EQUAL_INT(-7, errorMessage(validErrorCodeForenameTooLong[i]));
+		TEST_ASSERT_EQUAL_INT(-8, errorMessage(validErrorCodeSurnameTooLong[i]));
+		TEST_ASSERT_EQUAL_INT(-9, errorMessage(validErrorCodePasswordTooLong[i]));
+		TEST_ASSERT_EQUAL_INT(-10, errorMessage(validErrorCodeInvalidCharacterForename[i]));
+		TEST_ASSERT_EQUAL_INT(-11, errorMessage(validErrorCodeInvalidCharacterSurname[i]));
+		TEST_ASSERT_EQUAL_INT(-12, errorMessage(validErrorCodeTooManyDigits[i]));
+	}
+}
diff --git a/tests/test_LoginCustomer.c b/tests/test_LoginCustomer.c
new file mode 100644
index 0000000..a3f945b
--- /dev/null
+++ b/tests/test_LoginCustomer.c
@@ -0,0 +1,24 @@
+#include <unity.h>
+#include "../src/loginCustomer.c"
+#include "../src/customerMenu.c"
+#include "../src/helperFunctions.c"
+#include "../src/error.c"
+void setUp(){};
+void tearDown(){};
+void test_checkLogin()
+{
+	/*arrange*/
+	bool expected_test_values_compute_to_true[] = {4==4,true==true, 1==1, false==false, 'z'=='z', '='=='=',0x1A==0x1A};
+	int length_1 = sizeof(expected_test_values_compute_to_true)/sizeof(bool);
+
+	bool expected_test_values_compute_to_false[] = {4!=4,true==false,1==0,false==true,'z'=='x','!'==')',0x1A==0x2B};
+	int length_2 = sizeof(expected_test_values_compute_to_false)/sizeof(bool);
+	
+	/*act and assertions*/
+	for(int i=0;i<7;++i) {
+		TEST_ASSERT_TRUE(checkLogin(expected_test_values_compute_to_true[i]));
+	}	
+	for(int i=0;i<7;++i){
+		TEST_ASSERT_FALSE(checkLogin(expected_test_values_compute_to_false[i]));
+	}
+}
diff --git a/tests/test_createEmployeeAccount.c b/tests/test_createEmployeeAccount.c
index ad3ab81..b42ac75 100644
--- a/tests/test_createEmployeeAccount.c
+++ b/tests/test_createEmployeeAccount.c
@@ -2,7 +2,7 @@
 
 #include "unity.h"
 
-#include "createEmployeeAccount.h"
+#include "../src/createEmployeeAccount.c"
 
 void setUp(void)
 {
diff --git a/tests/test_employeeLogin.c b/tests/test_employeeLogin.c
index 87b9f27..6626a37 100644
--- a/tests/test_employeeLogin.c
+++ b/tests/test_employeeLogin.c
@@ -2,8 +2,8 @@
 
 #include "unity.h"
 
-#include "employeeLogin.h"
-
+#include "../src/employeeLogin.c"
+#include "../src/showGeneralInfoEmployee.c"
 void setUp(void)
 {
 }
diff --git a/tests/test_helperFunctions.c b/tests/test_helperFunctions.c
new file mode 100644
index 0000000..0b42d1a
--- /dev/null
+++ b/tests/test_helperFunctions.c
@@ -0,0 +1,213 @@
+#include <stdlib.h>
+#include <time.h>
+#include <string.h>
+#include <unity.h>
+#include "../src/helperFunctions.c"
+
+void test_calculateStringLength()
+{
+	char *testStrings[] = {"linux","table","book","men","woman","boy","girl","computer","old","new","water","fire","bright","dark","black","white"};	int expectedResults[] = {5,5,4,3,5,3,4,8,3,3,5,4,6,4,5,5};
+	int numberOfValues= sizeof(expectedResults) / sizeof(int);
+	for(int i=0;i<numberOfValues;++i){
+		TEST_ASSERT_EQUAL_INT(expectedResults[i], calculateStringLength(testStrings[i]));
+	}
+}
+
+void test_isLetterOfAlphabet()
+{
+	/*test block 1*/
+	char *testStringsToTrue[] = {"adhj","kasdlwq","vbeuqor","kalkwyynmakj","kakswxl","akljlxjkcyxyklj","asdjhuwpwe","xbcvddd","klajksdjkl","ghghgtie","kajsd"};
+	unsigned int numberOfElements = sizeof(testStringsToTrue) / sizeof(char *);
+	for(int i=0;i<numberOfElements;++i){
+		TEST_ASSERT_TRUE(isLetterOfAlphabet(testStringsToTrue[i]));
+	}
+	/*test block 2*/
+	char *testStringsToTrue_2[] = {"bcjyxhkjyxchjqwo","tree","garden","thinker","philosophy","linux","computer","lesson","teacher","table","drink","water","every", "Frank","city","economic","programming","task","smart","smarter","smartest","dumb","wood","animals","forest","display","hot","cold","ice","bear","keyboard","pair","pencil"};
+	numberOfElements = sizeof(testStringsToTrue_2) / sizeof(char *);
+	for(int i=0;i<numberOfElements;++i){
+		TEST_ASSERT_TRUE(isLetterOfAlphabet(testStringsToTrue_2[i]));
+	}
+	/*test block 3*/
+	char *testStringsToFalse[] = {"ashjdkj32123","4213jashj","laskdj2","1sbabjsdh","askjasdkjd0","123932131a","abcd2hutz","81287asjk231jkhs","aslkjasdlkjsd123","cbc451873"};
+	numberOfElements = sizeof(testStringsToFalse) / sizeof(char *);
+	for(int i=0;i<numberOfElements;++i){
+		TEST_ASSERT_FALSE(isLetterOfAlphabet(testStringsToFalse[i]));
+	}
+	/*test block 4*/
+	char *testStringsToFalse_2[] = {"1234","56789","00000010101010","3748927398273498","757575757","1726371238726","19237182937192837","875378612873621","128973192837","99494949499929292929292938382828","1827391237981273","7481263871236782136"};
+	numberOfElements = sizeof(testStringsToFalse_2) / sizeof(char *);
+	for(int i=0;i<numberOfElements;++i){
+		TEST_ASSERT_FALSE(isLetterOfAlphabet(testStringsToFalse_2[i]));
+	}
+}
+
+
+void test_toUnsignedInteger()
+{	
+	/*test block 1*/	
+	char *strings[] = {"111","123","542","994","9000","8384","6473","12345","57837","78387","93276","1000","8444","48484"};
+	int expected[] = {111,123,542,994,9000,8384,6473,12345,57837,78387,93276,1000,8444,48484};
+	int length = sizeof(expected)/sizeof(int);
+	for(int i=0;i<length;++i){
+		TEST_ASSERT_EQUAL_INT(expected[i], toUnsignedInteger(strings[i]));	
+	}
+
+	/*test block 2*/
+	char *strings_2[] = {"9999","99999","9","99","999","0","19","10","90","8765"};
+	int expected_2[] = {9999,99999,9,99,999,0,19,10,90,8765};
+	length = sizeof(expected_2)/sizeof(int);
+	for(int i=0;i<length;++i){
+		TEST_ASSERT_EQUAL_INT(expected_2[i], toUnsignedInteger(strings_2[i]));	
+	}
+
+	/*test block 3*/
+	char *strings_3[] = {"0","1","1","2","3","5","8","13","21","34","55","89","144","233"};
+	int expected_3[] = {0,1,1,2,3,5,8,13,21,34,55,89,144,233};
+	length = sizeof(expected_3)/sizeof(int);
+	for(int i=0;i<length;++i){
+		TEST_ASSERT_EQUAL_INT(expected_3[i], toUnsignedInteger(strings_3[i]));	
+	}
+
+}
+void test_everyCharacterIsDigit()
+{
+	/*test block 1*/
+	char *expectTrue[] = {"0","11","222","3333","4444","134132","12352378","12847273","1237873","9992475","987232","34723873278","578347823783","758378723","44293884742",
+	"3184123872873","8912892383","18282828","55757575757528282","123823883282383282575757283832","99999999999999999999999999999999999","128321378","81293982139823","21412323"
+	"575757575754646464648383838383","1298557648298219821398129381928391283918238912831283928391283129839281391283918238912391238912839182391239857517828"};
+	int length = sizeof(expectTrue)/sizeof(char *);
+	for(int i=0;i<length;++i){
+		TEST_ASSERT_TRUE(everyCharacterIsDigit(expectTrue[i]));
+	}
+
+	/*test block 2*/
+	char *expectFalse[] = {"a","bcd","dhdd","3asad87","askj","nxbdj","489sjk2kj","kjasjkd38234","aksjlas","bcbc838ch","akjsjkdjkq919191","askjsdakj492","kasjcncn","9919a19","cbajsh","askjajkd","ajshdasjh","jyxhyxjchyx","kasjdakj","vbvb88888888888888828282828282828askjh"};
+	length = sizeof(expectFalse)/sizeof(char *);
+	for(int i=0;i<length;++i){
+		TEST_ASSERT_FALSE(everyCharacterIsDigit(expectFalse[i]));
+	}
+}
+
+void test_power()
+{
+	/*test block 1*/
+	int testValues[] = {1,2,3,4,5,6,7,8,9,10};
+	int expectedValues[] = {1,4,9,16,25,36,49,64,81,100};
+	int length = sizeof(testValues)/sizeof(int);
+	const int exponent = 2;
+	for(int i=0;i<length;++i){
+		TEST_ASSERT_EQUAL_INT(expectedValues[i], power(testValues[i],exponent));	
+	}	
+
+	/*test block 2*/
+	int testValues_2[] = {11,12,13,14,15,16,17,18,19,20};
+	int expectedValues_2[] = {121,144,169,196,225,256,289,324,361,400};
+	length = sizeof(testValues_2)/sizeof(int);
+	for(int i=0;i<length;++i){
+		TEST_ASSERT_EQUAL_INT(expectedValues_2[i],power(testValues_2[i],exponent));
+	}
+	
+	/*test block 3*/
+	int testValues_3[] = {1,2,3,4,5,6,7,8,9,10};
+	int expectedValues_3[] = {1,8,27,64,125,216,343,512,729,1000};
+	const int exponent_2 = 3;
+	length = sizeof(testValues_3)/sizeof(int);
+	for(int i=0;i<length;++i){
+		TEST_ASSERT_EQUAL_INT(expectedValues_3[i],power(testValues_3[i],exponent_2));
+	}
+	/*test block 4*/
+	int testValues_4[] = {11,12,13,14,15,16,17,18,19,20};
+	int expectedValues_4[] = {1331,1728,2197,2744,3375,4096,4913,5832,6859,8000};
+	length = sizeof(testValues_4)/sizeof(int);
+	for(int i=0;i<length;++i){
+		TEST_ASSERT_EQUAL_INT(expectedValues_4[i],power(testValues_4[i],exponent_2));	
+	}
+	/*test block 5*/
+	int testValues_5[] = {0,0,19,2,4,5,11,54,32,12,77};
+	int exponents[] = {0,1,2,7,4,2,0,1,2,4,2};
+	int expectedValues_5[] = {0, 0, 361,128,256,25,1,54,1024,20736,5929};
+	length = sizeof(testValues_5)/sizeof(int);
+	for(int i=0;i<length;++i){
+		TEST_ASSERT_EQUAL_INT(expectedValues_5[i], power(testValues_5[i],exponents[i]));
+	}
+}
+
+void test_to_string() 
+{
+	/*initializing test values*/
+	char *result_1[] = {"0","1","2","3","4","5","6","7","8","9","10"};
+	char *result_2[] = {"500","502","504","506","508","510","512","514","516","518"};
+	char *result_3[] = {"1000","2000","3000","4000","5000","6000","7000","8000","9000","10000"};
+	char *result_4[] = {"9999","8999","7999","6999","5999","4999","3999","2999","1999","999"};
+	char *result_5[] = {"1000000","2000000","3000000","4000000","5000000","6000000","7000000",
+			    "8000000","9000000","10000000"};
+
+	/*assertions*/
+	for(int i=0;i<=10;++i){
+		TEST_ASSERT_EQUAL_STRING(result_1[i],to_string(i));
+	}	
+	
+	for(int i=0, j=500;i<10;++i,j+=2){
+		TEST_ASSERT_EQUAL_STRING(result_2[i],to_string(j));
+	}
+
+	for(int i=0, j=1000;i<10;++i,j+=1000){
+		TEST_ASSERT_EQUAL_STRING(result_3[i],to_string(j));	
+	}
+	
+	for(int i=0, j=9999;i<10;++i,j-=1000){
+		TEST_ASSERT_EQUAL_STRING(result_4[i], to_string(j));
+	}
+	for(int i=0, j=1000000;i<10;++i,j+=1000000){
+		TEST_ASSERT_EQUAL_STRING(result_5[i],to_string(j));
+	}
+
+}
+
+
+void test_generateCheckString() 
+{
+	/*test block 1*/
+	int numbers_1[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25};
+	char *strings_1[] = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
+	char *result_1[] = {"0=a","1=b","2=c","3=d","4=e","5=f","6=g","7=h","8=i","9=j","10=k","11=l","12=m","13=n","14=o","15=p","16=q","17=r",                            "18=s","19=t","20=u","21=v","22=w","23=x","24=y","25=z"};
+	for(int i=0;i<26;++i){
+		TEST_ASSERT_EQUAL_STRING(result_1[i],generateCheckString(numbers_1[i],*(strings_1+i)));
+	}
+	/*test block 2*/
+	int numbers_2[] = {0,1,1,2,3,5,8,13,21,34,55,89,144,233,377,610,987,1597,2584,4181,6765,10946,17711,28657,46368,75025};
+	char *strings_2[] = {"z","zy","zyx","zyxw","zyxwv","zyxwvu","zyxwvut","zyxwvuts","zyxwvutsr","zyxwvutsrq","zyxwvutsrqp",
+			     "zyxwvutsrqpo","zyxwvutsrqpon","zyxwvutsrqponm","zyxwvutsrqponml","zyxwvutsrqponmlk",
+			     "zyxwvutsrqponmlkj","zyxwvutsrqponmlkji","zyxwvutsrqponmlkjih","zyxwvutsrqponmlkjihg","zyxwvutsrqponmlkjihgf",
+			      "zyxwvutsrqponmlkjihgfe","zyxwvutsrqponmlkjihgfed","zyxwvutsrqponmlkjihgfedc","zyxwvutsrqponmlkjihgfedcb",
+			      "zyxwvutsrqponmlkjihgfedcba"};
+	char *result_2[] = {"0=z","1=zy","1=zyx","2=zyxw","3=zyxwv","5=zyxwvu","8=zyxwvut","13=zyxwvuts","21=zyxwvutsr","34=zyxwvutsrq",
+	                    "55=zyxwvutsrqp","89=zyxwvutsrqpo","144=zyxwvutsrqpon","233=zyxwvutsrqponm","377=zyxwvutsrqponml",
+			    "610=zyxwvutsrqponmlk","987=zyxwvutsrqponmlkj","1597=zyxwvutsrqponmlkji","2584=zyxwvutsrqponmlkjih",
+			    "4181=zyxwvutsrqponmlkjihg","6765=zyxwvutsrqponmlkjihgf","10946=zyxwvutsrqponmlkjihgfe",
+			    "17711=zyxwvutsrqponmlkjihgfed","28657=zyxwvutsrqponmlkjihgfedc","46368=zyxwvutsrqponmlkjihgfedcb",
+			    "75025=zyxwvutsrqponmlkjihgfedcba"};
+	for(int i=0;i<26;++i){
+		TEST_ASSERT_EQUAL_STRING(result_2[i],generateCheckString(numbers_2[i],*(strings_2+i)));	
+	}
+	/*test block 3*/
+	srand(time(0));
+	int random_number=0;
+	char *random_numbers_strings[20];
+	int random_numbers[20];
+	for(int i=0;i<20;++i){
+		random_number = (rand() % 100) + 1;
+		random_numbers_strings[i] = to_string(random_number);
+		random_numbers[i] = random_number;
+	}
+	char *strings_3[] = {"tree","plant","tea","programming","assembler","unix","BSD","snow","mountain","table","wood","forest", "calculator","book","light","keyboard","old","paper","pencil","voltage"};
+	char *result_3[20];
+	for(int i=0;i<20;++i){
+		random_numbers_strings[i] = strcat(random_numbers_strings[i],"=");
+		result_3[i] = strcat(random_numbers_strings[i],strings_3[i]);
+		printf("%s\n",result_3[i]);
+	}
+	for(int i=0;i<20;++i){
+		TEST_ASSERT_EQUAL_STRING(result_3[i],generateCheckString(random_numbers[i],strings_3[i]));
+	}
+}
diff --git a/tests/test_mainMenu.c b/tests/test_mainMenu.c
index 97cc069..5ae1670 100644
--- a/tests/test_mainMenu.c
+++ b/tests/test_mainMenu.c
@@ -2,7 +2,7 @@
 
 #include "unity.h"
 
-#include "mainMenu.h"
+#include "../src/mainMenu.c"
 
 void setUp(void)
 {
diff --git a/tests/test_showGeneralInfoEmployee.c b/tests/test_showGeneralInfoEmployee.c
index c28c306..0f2555e 100644
--- a/tests/test_showGeneralInfoEmployee.c
+++ b/tests/test_showGeneralInfoEmployee.c
@@ -2,7 +2,7 @@
 
 #include "unity.h"
 
-#include "showGeneralInfoEmployee.h"
+#include "../src/showGeneralInfoEmployee.c"
 
 void setUp(void)
 {