Modification of the function collectCustomerProperties. It now contains a call to balanceToDouble(). The reason is: The function scanf() is eliminated. Instead, the input is completely handled by getchar(). Each character is stored consecutively. Thus it can be the parameter for balanceToDouble().

src/createCustomer.c

@@ -18,7 +18,7 @@ void collectCustomerProperties()
 	int letterCounter = 0;
 	int letterMaximum = 15;
 	char userInput=' ';
-	bool inputTooLong = false;
+	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'){
@@ -58,6 +58,7 @@ void collectCustomerProperties()
 		errorMessage(-11);
 	}
 	printf("Enter password (max. 20 letters):\n");
+	letterMaximum = 20;
 	while(letterCounter<letterMaximum && (userInput=getchar())!='\n'){
 		*(instance.password+letterCounter) = userInput;
 		++letterCounter;
@@ -68,12 +69,40 @@ void collectCustomerProperties()
 	}
 	if(inputTooLong){
 		errorMessage(-9);
-	}
+	}else{
 	*(instance.password+letterCounter) = '\0';
-	letterCounter = 0;
-	printf("Enter balance:\n");
-	scanf("%f",&instance.balance);
+	}
 	
+	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){
+		puts("Input too long.");
+		exit(-1);
+		//call errorMessage(-10);	
+	}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);

src/customerProperties.h

@@ -6,6 +6,6 @@ typedef struct Customer
 	char *IDAsString;
 	char *password;
 	char *forename, *surname;
-	float balance;	
+	double balance;	
 }customer_t;
 #endif

src/error.c

@@ -46,12 +46,12 @@ int errorMessage(int errorCode)
 		exit(-1);
 		break;
 	case -10:
-		puts("You have entered a digit for your forename. This is not allowed. Aborting!");
+		puts("You have entered an invalid character [ä,ö,ü, special characters] for your forename. This is not allowed. Aborting!");
 		returnValue = -10;
 		exit(-1);
 		break;
 	case -11:
-		puts("You have entered a digit for your surname. This is not allowed. Aborting!");
+		puts("You have entered an invalid character [ä,ö,ü, special characters] for your surname. This is not allowed. Aborting!");
 		returnValue = -11;
 		exit(-1);
 		break;

src/helperFunctions.c

@@ -71,7 +71,7 @@ bool everyCharacterIsDigit(char *string)
 {
 	bool onlyDigits = true;
 	for(int i=0;*(string+i)!='\0';++i){
-		if(*(string+i)<'0'||*(string+i)>'9'){
+		if( !(*(string+i)>='0'&&*(string+i)<='9') && *(string+i)!='.'){
 			onlyDigits = false;
 			break;
 		}

test/test_helperFunctions.c

@@ -2,7 +2,6 @@
 #include <time.h>
 #include <string.h>
 #include <unity.h>
-#include "unity_config.h"
 #include "../src/helperFunctions.c"
 
 void test_isLetterOfAlphabet()