Diagnostic Log

A debug flag can print the values that explain how a result was produced.

diagnostic_log.c

#include <stdio.h>

int main(void) {
    int debug = ;
    int width = 6;
    int height = 4;
    int area = width * height;

    if (debug) {
        printf("debug width=%d height=%d\n", width, height);
    }

    printf("area=%d\n", area);
    return 0;
}

#include <stdio.h>

int main(void) {
    int debug = ;
    int width = 6;
    int height = 4;
    int area = width * height;

    if (debug) {
        printf("debug width=%d height=%d\n", width, height);
    }

    printf("area=%d\n", area);
    return 0;
}

debug flag A flag lets diagnostic output be turned on while leaving the normal result unchanged.

trace value Printing intermediate values can confirm which path the program followed.