C If Else

The if statement

An if statement checks a condition inside parentheses. If that condition is true (any non-zero value), the block of code in the curly braces runs. If it is false, the block is skipped entirely.

#include <stdio.h>

int main() {
    int temperature = 30;

    if (temperature > 25) {
        printf("It is a hot day.\n");
    }
    return 0;
}

Adding else

The else keyword gives your program a fallback. When the if condition is false, the else block runs instead. Exactly one of the two blocks will always run.

#include <stdio.h>

int main() {
    int hour = 20;

    if (hour < 18) {
        printf("Good day.\n");
    } else {
        printf("Good evening.\n");
    }
    return 0;
}

The else if ladder

Sometimes you have more than two possibilities. You can chain conditions with else if. C checks each condition from top to bottom and runs the first block whose condition is true; the rest are skipped.

#include <stdio.h>

int main() {
    int score = 82;

    if (score >= 90) {
        printf("Grade A\n");
    } else if (score >= 75) {
        printf("Grade B\n");
    } else {
        printf("Grade C\n");
    }
    return 0;
}

• if runs its block only when the condition is true.
• else if lets you test another condition when earlier ones failed.
• else is the catch-all that runs when nothing above matched.