refactoring: rename variables for better understanding, write comment to explain function generateCheckString(), optimize intendation

src/StringManipulation.c

@@ -11,13 +11,13 @@ char *to_string(int number)
 	}
 	else
 	{
-	int cpy = number, len = 0;
-	while(number>0){
+		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){
+		}
+		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;
 	}
@@ -26,18 +26,19 @@ char *to_string(int number)
 	}
 }
 
-char *generateCheckString(int ID, char *password)
+char *generateCheckString(int customerID, char *customerPassword)
 {
-	char *IDString = to_string(ID);
+	/*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 string is: [ID]=[PASSWORD]*/
+	char *IDString = to_string(customerID);
 	int IDLength = strlen(IDString);
-	int passwordLength = strlen(password);
-	/*the checkString has this form: ID=password, so in order to calculate its length the length of the ID, one byte for the =, the length of the password and
-	 * one byte for '\0' are needed.*/
+	int passwordLength = strlen(customerPassword);
 	int checkStringLength = IDLength + 1 + passwordLength + 1;
 	char *checkString = calloc(checkStringLength, sizeof(char));
 	checkString = strcat(IDString, "=");
-	checkString = strcat(checkString, password);
+	checkString = strcat(checkString, customerPassword);
 	*(checkString+checkStringLength) = '\0';
-	return checkString;:w
-
+	return checkString;
 }