The if statement

Learn how to check a condition with if and the code block.

The if statement

The if statement runs a code block when a condition is true. The condition goes in parentheses; if it's true (non-zero) the block runs.

int score = 80;
if (score >= 50) {
    printf("Passed\n");
}

Here >= is a comparison operator. Common operators: == equal, != not equal, < less, > greater, <= less or equal, >= greater or equal. When the condition is false the block is skipped.

Single-line if

When the block has a single statement, braces are optional. But using them is a good habit; adding a statement later won't break anything.

int n = 7;
if (n % 2 == 0)
    printf("Even\n");
if (n % 2 != 0)
    printf("Odd\n");

The % operator gives the division remainder; n % 2 is used to check even/odd. Each if is independent; both may run.

Exercise Is the number even or odd?

Write a C program. Declare int n = 7;. Use if to check n % 2 == 0; if true print printf("Even\n");. Also use if to check n % 2 != 0; if true print printf("Odd\n");. Put #include <stdio.h> at the top.

Show example solution

#include <stdio.h>

int main(void) {
    int n = 7;
    if (n % 2 == 0) {
        printf("Even\n");
    }
    if (n % 2 != 0) {
        printf("Odd\n");
    }
    return 0;
}

Test yourself

When does if (score >= 50) run?
```
if (score >= 50) {
    printf("Passed");
}
```
- When score is 50 or greater
- When score is less than 50
- Always
- Never
Show answer

When score is 50 or greater — >= accepts 50 and above.

Write the equality operator

if (a ____ b) {
    printf("Equal");
}

Show answer

if (a == b) {
    printf("Equal");
}

Match the operators

==

Equal
!=

Not equal
>=

Greater or equal
<

Less

Next lesson: else and else if

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