In C, the concepts of true and false are represented using integers. The integer value 0 is considered false, and any non-zero value is considered true. However, C99 introduced the <stdbool.h> header, which defines the _Bool type and introduces the bool type and the constants true and false. Here are examples using both approaches:

Using integers:

#include <stdio.h>

int main() {
    // Using integers
    int trueValue = 1;
    int falseValue = 0;

    if (trueValue) {
        printf("This statement is true\n");
    } else {
        printf("This statement is false\n");
    }

    if (falseValue) {
        printf("This statement is true\n");
    } else {
        printf("This statement is false\n");
    }

    return 0;
}

In this example, the conditions inside the if statements are evaluated based on the truthiness or falsiness of the integer values.

Using <stdbool.h>:

#include <stdio.h>
#include <stdbool.h>

int main() {
    // Using <stdbool.h>
    bool trueValue = true;
    bool falseValue = false;

    if (trueValue) {
        printf("This statement is true\n");
    } else {
        printf("This statement is false\n");
    }

    if (falseValue) {
        printf("This statement is true\n");
    } else {
        printf("This statement is false\n");
    }

    return 0;
}

Here, the <stdbool.h> header is included, and the bool type is used with true and false constants. This makes the code more readable and expressive.

Both examples will produce the same output:

This statement is true
This statement is false

In C, it's common to see the integer approach, especially in older codebases. However, using bool from <stdbool.h> provides better readability and is preferred in modern C programming.