运行时检查失败＃2-变量'tempID'周围的堆栈已损坏

Question

I recently started coding in c, and during coding I encountered this run-time error which I can't find the solution to. It either displays this runtime error, or else stops after the scanf in the case where the customer is found, you choose what you want to edit, and then enter the new information.

Example:

• inputted ID:322993
• FOUND
• Pressed [1] to edit the ID
• Input the new ID
• program gets stuck

Here is the code:

void modifyCustomer(){
    int counter=0;
    long int tempID=0;
    flag found = false;
    fflush(stdin);
    printf("Enter Customer ID\n");
    scanf("%lld", &tempID);
    do{
        char option_str[200];
        int option = 0;
        char *not_valid;
        if(tempID == customers[counter].customerID){
            printf("Customer found!\n");
            found = true;
            do{
                fflush(stdin);
                printf("Choose what to modify:\n 1. ID\n 2. Name\n 3. Surname\n 4. Address\n 5. Mobile\nOption: ");
                scanf("%s", &option_str);
                option = strtol(option_str, &not_valid, 10);
                fflush(stdin);
                if (*not_valid != '\0') {
                    printf("%s is not valid.\n", not_valid);
                } else{
                    switch(option){
                    case 1:
                        printf("Enter new ID:\n");
                        scanf("%d\n", &customers[counter].customerID);
                        printf("Customer Modified Successfully!\n");
                        break;
                    case 2:
                        printf("Enter new Name:\n");
                        scanf("%s\n", &customers[counter].customerName);
                        printf("Customer Modified Successfully!\n");
                        break;
                    case 3:
                        printf("Enter new Surname:\n");
                        scanf("%s\n", &customers[counter].customerSurname);
                        printf("Customer Modified Successfully!\n");
                        break;
                    case 4:
                        printf("Enter new Address:\n");
                        scanf("%s\n", &customers[counter].customerAddress);
                        printf("Customer Modified Successfully!\n");
                        break;
                    case 5:
                        printf("Enter new Mobile:\n");
                        scanf("%lld\n", &customers[counter].customerMobile);
                        printf("Customer Modified Successfully!\n");
                        break;
                    default:
                        printf("You did not enter a valid Number. Please re-enter your Input \n");
                        break;
                    }
                }
            }while((option <1) || (option > 5));
        }
        else{
            counter++;
        }
    }while((found != true) && (counter < (custNum-1)));
    if (found == false)
        printf("Customer not found!\n");
}

Why does this happen?

Answer 1

The %lld format specifier is for a long long . You've declared a long int so may be trying to write to a larger type than you have storage for. The effects of this are undefined but writing over the next stack variable is very likely if sizeof(long int) != sizeof(long long) on your platform.

You can fix this by either changing tempID to be of type long int or by changing the format specifier you use to %ld .