快速预订问题

#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 selectionnn");
printf("1. Enter First Namen");
printf("2. Enter Last Namen");
printf("3. Enter Addressn");
printf("4. Enter Phone Numbernn");
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;
}

这段代码在我选择一个条目之后，在我输入一个条目并按enter键之后，它崩溃了，说变量"entry"周围的堆栈损坏了。我很确信我用的是fwrite函数。我知道fwrite查找的第一个参数是指向要写入的元素数组的指针，但我想我现在只是感到困惑。