How to Use If Else in C: Simple Guide with Examples

In C, use if to run code when a condition is true, and else to run code when it is false. The syntax is if (condition) { ... } else { ... }. This lets your program choose between two paths based on conditions.

Syntax

The if else statement lets you run different code based on a condition.

• if (condition): Checks if the condition is true.
• { ... }: Code inside braces runs if the condition is true.
• else: Runs if the if condition is false.
• { ... }: Code inside braces runs if the else part is executed.

c

if (condition) {
    // code runs if condition is true
} else {
    // code runs if condition is false
}

Example

This example checks if a number is positive or not and prints a message accordingly.

c

#include <stdio.h>

int main() {
    int number = 5;

    if (number > 0) {
        printf("Number is positive\n");
    } else {
        printf("Number is zero or negative\n");
    }

    return 0;
}

Output

Number is positive

Common Pitfalls

Common mistakes when using if else in C include:

• Forgetting braces { } when you have multiple statements inside if or else. This causes only the first statement to be controlled by the condition.
• Using = (assignment) instead of == (comparison) in the condition.
• Missing semicolons ; after statements.

c

/* Wrong: missing braces causes only first printf to be conditional */
if (number > 0)
    printf("Positive\n");
    printf("Checked number\n");  // runs always

/* Right: braces group both statements */
if (number > 0) {
    printf("Positive\n");
    printf("Checked number\n");
}

Quick Reference

Tips for using if else in C:

• Always use braces { } for clarity and to avoid bugs.
• Use == to compare values, not =.
• Indent your code inside if and else blocks for readability.
• You can chain multiple conditions using else if.

Key Takeaways

Use if to run code when a condition is true and else when it is false.

Always use braces { } to group multiple statements inside if or else blocks.

Use == for comparison, not = which assigns values.

Indent your code inside conditions for better readability.

You can add more conditions with else if for multiple choices.