The if statement

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

The if statement

To run code when a condition holds you use the if statement. You write a boolean expression in parentheses; when it is true the curly brace block runs, when false it is skipped.

For example, if (age >= 18) { Console.WriteLine("Can drive"); } prints the message when age is 18 or above. The condition always evaluates to true or false; nothing in between.

Conditions with logical operators

To combine several conditions you use && (and), || (or) and ! (not). if (age >= 18 && age <= 65) returns true when age is both 18 or above and 65 or below.

&& short-circuits: if the left side is false the right side is not evaluated. This makes safe checks like if (p != null && p.Length > 0) easy to write; if the left is false the right never runs.

Exercise Write the pass condition

Declare a score variable with the value 60. Use if to check score >= 50; when the condition holds, print "passed" with Console.WriteLine.

Show example solution

Write if (score >= 50) { Console.WriteLine("passed"); }
Example solution:
using System;

class Program
{
    static void Main()
    {
        int score = 60;
        if (score >= 50)
        {
            Console.WriteLine("passed");
        }
    }
}

Test yourself

With int age = 16; what does if (age >= 18) do?
```
int age = 16;
if (age >= 18) Console.WriteLine("adult");
```
- Prints nothing
- Prints 'adult'
- Raises a compile error
- Loops forever
Show answer

Prints nothing — Correct. 16 >= 18 is false, so the block is skipped.

Write the condition

int score = 75;
if (____)
{
    Console.WriteLine("passed");
}

Show answer

int score = 75;
if (score >= 50)
{
    Console.WriteLine("passed");
}

Match each operator to its meaning

&&

And (both true)
||

Or (at least one true)
!

Not (flips the value)
>=

Greater than or equal

Next lesson: else and else if

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