How can C language determine if a floating-point number is an integer?

In the C language, you can use the functions in the math.h header file to determine if a floating-point number is an integer. Here is an example code:

#include <stdio.h>
#include <math.h>

int is_integer(float num) {
    return num == floor(num);
}

int main() {
    float num = 3.0;

    if(is_integer(num)) {
        printf("The number is an integer.\n");
    } else {
        printf("The number is not an integer.\n");
    }

    return 0;
}

In the code above, the is_integer function uses the floor function to round a floating point number and then compare it with the original number. If they are the same, it means that the floating point number is an integer.