Question

#include <stdio.h>

#pragma pack(push)
#pragma (1)

typedef struct contact {    
    char firstname [40];    
    char lastname [40]; 
    char address [100]; 
    char phone[10];
}contact;

#pragma pack(pop)

int main ()
{   FILE *pFile;
    contact entry = {"", "", "", ""};
    char choice;

    pFile = fopen("C:\\contacts.txt", "w+");

if(!pFile){
    printf("File could not be open");
    return 1;
    }

printf("Choose a selection\n\n");
printf("1. Enter First Name\n");
printf("2. Enter Last Name\n");
printf("3. Enter Address\n");
printf("4. Enter Phone Number\n\n");
scanf( "%d", &choice);

switch (choice){

     case 1:
        printf("First name: \n");     
        fgets(entry.firstname, sizeof(entry.firstname),pFile);
        break;
     case 2:
        printf("Last name: \n");      
        fgets(entry.lastname, sizeof(entry.lastname),pFile);
        break;
     case 3:
        printf("Address: \n");    
        fgets(entry.address, sizeof(entry.address),pFile);
        break;
     case 4:
        printf("Phone Number: \n");   
        fgets(entry.phone, sizeof(entry.phone),pFile);
        break;
     default:
        printf(" No Choice selected, Ending Address Book Entry system");
        break;
    }
        fwrite(&entry, sizeof(contact), 1, pFile);

        printf("Enter a new contact?");
        scanf("%s", &choice);

     //while(choice != 'n');

fclose(pFile);

getchar();
return 0;
}

This code after I choose an entry and after I put an entry in and press enter it crashes saying Stack around the variable ‘entry’ was corrupted. I’m fairly confident that it is my fwrite function that I’m using. I know the first parameter fwrite looks for is a pointer to an array of elements to be written but I think I’m just confused right now. Any help would be much appreciated.

Answer 1

You should change all your

fgets(entry.firstname, sizeof(entry.firstname),pFile);

to

fgets(entry.firstname, sizeof(entry.firstname),stdin);

Because you’re reading from the console, not the file.

Also, with

scanf("%s", &choice);

and

scanf( "%d", &choice);

you’re trying to read a string and a digit and store it in a char. They both should be

scanf("%c", &choice);

That said, you should think about rewriting this using ifstream, cin, getline, and std::string to make your life easier if you’re not looking for maximum performance.