If Else in C

Branching with if and else in C is straightforward.

#include <stdio.h>

int main() {
    // Here's a basic example.
    if (7 % 2 == 0) {
        printf("7 is even\n");
    } else {
        printf("7 is odd\n");
    }

    // You can have an `if` statement without an else.
    if (8 % 4 == 0) {
        printf("8 is divisible by 4\n");
    }

    // Logical operators like `&&` and `||` are often
    // useful in conditions.
    if (8 % 2 == 0 || 7 % 2 == 0) {
        printf("either 8 or 7 are even\n");
    }

    // In C, you can't declare variables in the if statement,
    // so we declare it before the condition.
    int num = 9;
    if (num < 0) {
        printf("%d is negative\n", num);
    } else if (num < 10) {
        printf("%d has 1 digit\n", num);
    } else {
        printf("%d has multiple digits\n", num);
    }

    return 0;
}

To compile and run the program:

$ gcc if-else.c -o if-else
$ ./if-else
7 is odd
8 is divisible by 4
either 8 or 7 are even
9 has 1 digit

Note that in C, you need parentheses around conditions, and the braces are optional for single-statement blocks (though using them is generally recommended for clarity).

C doesn’t have a ternary if operator like ?:, but it does have the ternary conditional operator, which can be used for simple conditional expressions:

int x = (condition) ? value_if_true : value_if_false;

However, for more complex conditions, a full if statement is necessary.

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If Else in C