How do I repeat entering data in a struct using C? - c

Question

I'm new to C, and currently trying to practice on some simple codes, and I'm currently stuck with that next one.
After entering the first customer data, and repeat the code... View_customer function fails to show the saved data, and when I try to go to enter a second account data, it fails at the second entry.
#include<stdio.h>
#include<stdlib.h>
typedef struct cust{
char name[60];
int acc_no,age;
char address[60];
char citizenship[15];
double phone;
char acc_type[10];
} cust;
void new_account(int num);
void view_account(int num);
int main()
{
cust customers[10];
char answer;
int n;
int cutomer_number=1;
int cutomer_num2;
printf("Welcome To The program X: \n");
do{
printf("\n How can we serve you today? \n 1.Create a new account \n 2.Print an existing Account info \n ");
scanf("%d",&n);
if (n==1)
{
new_account(cutomer_number);
cutomer_number++;
}else {
printf("Please enter your Cust number: ");
scanf(" %d",&cutomer_num2);
view_account(cutomer_num2);
};
printf("\n Press Y to continue. Press any Key To Exit: ");
scanf(" %c",&answer);
}while (answer == 'Y' || answer == 'y');
return 0;
}
void view_account(int n)
{
cust customers[n];
printf("Your name is %s \n ", customers[n].name);
printf("Your age is %d \n", customers[n].age);
printf("Your address is %s \n", customers[n].address);
printf("Your citizenship is %s \n", customers[n].citizenship);
printf("Your phone number is %f \n", customers[n].phone);
printf("Your account type is %s \n", customers[n].acc_type);
};
void new_account(int n)
{
cust customers[n];
customers[n].acc_no = n;
printf("You are the customer number %d \n", customers[n].acc_no);
printf("Please, Enter your name: ");
scanf("%s", &customers[n].name);
printf("Please, Enter your age:");
scanf(" %d", &customers[n].age);
printf("Please, Enter your address: ");
scanf(" %s", &customers[n].address);
printf("Please, Enter your citizenship: ");
scanf(" %s", &customers[n].citizenship);
printf("Please, Enter your phone number: ");
scanf(" %f", &customers[n].phone);
printf("Please, Enter your account type: ");
scanf(" %s", &customers[n].acc_type);
}
>

Answer 1

Each of your three functions declares its own customers array variable, so each of them has their own memory for the customer data. Moreover, the array of new_account goes out of scope at the end of the function, so you can no longer safely access the data. Because of how C compilers typically work, the customer data is not immediately erased from memory, so your view_account function might still be able to read it, but that is what is called "undefined behavior". Which means it might work, or it might not.
Try to pass down the array from the main function to the other two functions in parameters. Or, to make things simpler at first, you could also turn the local customers variable of main into a global variable.
cust customers[10];
int main(int argc, char *argv[])
{
char answer;
int n;
int cutomer_number=1;
int cutomer_num2;
printf("Welcome To The program X: \n");
...
}
void view_account(int n) {
printf("Your name is %s \n ", customers[n].name);
...
}
void new_acccount(int n)
{
customers[n].acc_no = n;
...
}
Note that there are further issues in your code, like not checking the return value of scanf or overflowing the char arrays of the struct if you enter too many characters (missing bounds and length checking), or being able to enter more than 10 customers and accessing out of bounds of the customers array, or not using customers[0] (because your customer_number starts at 1, but array indices are 0-based). But I will not go into further details here to keep the answer focused.