How to compare the size of strings in the C language?

In C language, string comparison can be achieved using the strcmp function. The prototype of the strcmp function is:

int strcmp(const char *str1, const char *str2);

This function compares two strings, str1 and str2, and returns a negative integer if str1 is smaller than str2, a positive integer if str1 is larger than str2, and 0 if str1 is equal to str2.

Here is an example code comparing the size of two strings:

#include <stdio.h>
#include <string.h>

int main() {
    char str1[20] = "Hello";
    char str2[20] = "World";

    int result = strcmp(str1, str2);

    if (result < 0) {
        printf("str1 is less than str2\n");
    } else if (result > 0) {
        printf("str1 is greater than str2\n");
    } else {
        printf("str1 is equal to str2\n");
    }

    return 0;
}

The output is:

str1 is less than str2