If Statement in C#

In this tutorial, we will learn about if statements in C#. We will cover the basics of conditional execution using if statements.

What is an If statement

An if statement is a conditional statement that executes a block of code if a specified condition is true.

Syntax

The syntax for the if statement in C# is:

if (condition) {
    // Code block to execute if condition is true
}

The if statement evaluates the specified condition. If the condition is true, the code block inside the if statement is executed; otherwise, it is skipped.

The following is the flowchart of how execution flows from start to the end of an if statement.

Flowchart of If Statement

Example 1: Checking if a Number is Even

  1. Declare an integer variable num.
  2. Assign a value to num.
  3. Use an if statement to check if num is even.
  4. Print a message indicating whether num is even or not.

C# Program

using System;
class Program {
    static void Main() {
        int num = 10;
        if (num % 2 == 0) {
            Console.WriteLine("{0} is even.", num);
        }
    }
}

Output

10 is even.

Example 2: Checking if a String Starts with a Specific Value

  1. Declare a string variable str.
  2. Assign a value to str.
  3. Use an if statement to check if str starts with a specific value.
  4. Print a message indicating the result of the check.

C# Program

using System;
class Program {
    static void Main() {
        string str = "Hello, world!";
        if (str.StartsWith("Hello")) {
            Console.WriteLine("String starts with 'Hello'.");
        }
    }
}

Output

String starts with 'Hello'.

Example 3: Checking if a Number is Positive

  1. Declare an integer variable num.
  2. Assign a value to num.
  3. Use an if statement to check if num is positive.
  4. Print a message indicating whether num is positive or not.

C# Program

using System;
class Program {
    static void Main() {
        int num = -5;
        if (num > 0) {
            Console.WriteLine("{0} is positive.", num);
        }
    }
}

Output