Assert Condition

A checked condition can protect the line that depends on it.

assert_condition.c

#include <stdio.h>

int main(void) {
    int value = ;
    int ok = value > 0;

    if (ok) {
        int quotient = 120 / value;
        printf("ok=%d quotient=%d\n", ok, quotient);
    } else {
        printf("ok=%d quotient=skipped\n", ok);
    }

    return 0;
}

#include <stdio.h>

int main(void) {
    int value = ;
    int ok = value > 0;

    if (ok) {
        int quotient = 120 / value;
        printf("ok=%d quotient=%d\n", ok, quotient);
    } else {
        printf("ok=%d quotient=skipped\n", ok);
    }

    return 0;
}

#include <stdio.h>

int main(void) {
    int value = ;
    int ok = value > 0;

    if (ok) {
        int quotient = 120 / value;
        printf("ok=%d quotient=%d\n", ok, quotient);
    } else {
        printf("ok=%d quotient=skipped\n", ok);
    }

    return 0;
}

precondition A precondition is a fact the next operation needs before it is safe.

checked path Checking the condition first lets the program report the problem instead of using a bad value.