C语言赌场电话簿程序出现「comparison between pointer and integer」错误求助

Hey there! Welcome to C programming—great choice picking a practical project like a casino phonebook to learn with. Let's tackle that error and build your basic version step by step.

First, let's fix the small issues in the code you shared:

• The main() function should have a return type of int (this is standard in C)
• Your printf string is missing a closing quote and newline, which will cause a compile error right off the bat

Here's the corrected starting snippet:

#include <stdio.h>

int main() {
    printf("Please Select Department [Security, Food & Beverage, Hotel]: ");
    // We'll add input handling and department logic here next
    return 0;
}

Why You're Seeing the "comparison between pointer and integer" Error #

That error almost always happens when you try to compare a string (which is a pointer to a char array in C) with a single char (an integer type) or when you use == to compare strings directly. For example, if you tried something like this:

// Wrong way - triggers the error
char user_choice;
scanf("%c", &user_choice);
if (user_choice == "Security") { // Comparing a char (integer) to a string pointer
    // ...
}

Or even this (which doesn't trigger the same error but still doesn't work as intended):

// Still wrong - compares pointer addresses, not string content
char user_input[50];
scanf("%s", user_input);
if (user_input == "Security") { 
    // ...
}

The Fix: Use strcmp() for String Comparisons #

In C, to compare the content of two strings, you need to use the strcmp() function from the <string.h> header. This function returns 0 if the two strings are identical.

Full Basic Working Example #

Here's a complete basic version of your casino phonebook that avoids the error:

#include <stdio.h>
#include <string.h> // Required for strcmp()

int main() {
    char department[50];
    
    printf("Welcome to the Casino Phonebook!\n");
    printf("Please Select a Department [Security, Food & Beverage, Hotel]: ");
    scanf("%s", department); // Note: This won't handle spaces in "Food & Beverage" - we can fix that later!

    // Compare user input to department names using strcmp()
    if (strcmp(department, "Security") == 0) {
        printf("\nSecurity Department Phones:\n");
        printf("- Main Desk: 555-1234\n");
        printf("- Patrol Team: 555-1235\n");
    } 
    else if (strcmp(department, "Hotel") == 0) {
        printf("\nHotel Department Phones:\n");
        printf("- Front Desk: 555-2345\n");
        printf("- Housekeeping: 555-2346\n");
    }
    // Handle "Food & Beverage" - since scanf("%s") stops at spaces, we'll use a workaround for now
    else if (strcmp(department, "Food") == 0) {
        printf("\nFood & Beverage Department Phones:\n");
        printf("- Kitchen: 555-3456\n");
        printf("- Bar: 555-3457\n");
    }
    else {
        printf("\nSorry, that department isn't in our phonebook yet!\n");
    }

    return 0;
}

Quick Notes for Your Next Steps #

• To handle department names with spaces (like "Food & Beverage"), use fgets() instead of scanf("%s")—just remember to trim the newline character that fgets() adds.
• Later, you can expand this by storing departments and their phones in arrays or structs to make the code cleaner and easier to extend.

内容的提问来源于stack exchange，提问作者Koquan