What are control statements in C#?

Control statements in C# determine the flow of program execution by specifying which code blocks to execute based on conditions or how many times to repeat certain operations. These statements are fundamental building blocks that allow developers to create dynamic and responsive applications.

C# provides several types of control statements that can be categorized into conditional statements (if, if-else, switch) and loop statements (for, while, do-while, foreach). Let's explore the main control statements with practical examples.

if Statement

An if statement executes a block of code only when a specified boolean condition evaluates to true.

Syntax

if(boolean_expression) {
   // statement(s) will execute if the boolean expression is true
}

Example

using System;

class Program {
   public static void Main() {
      int age = 18;
      
      if(age >= 18) {
         Console.WriteLine("You are eligible to vote.");
      }
      
      Console.WriteLine("Program continues...");
   }
}

The output of the above code is −

You are eligible to vote.
Program continues...

if-else Statement

An if-else statement provides an alternative path of execution when the boolean condition is false.

Syntax

if(boolean_expression) {
   // statement(s) will execute if the boolean expression is true
} else {
   // statement(s) will execute if the boolean expression is false
}

Example

using System;

class Program {
   public static void Main() {
      int number = 15;
      
      if(number % 2 == 0) {
         Console.WriteLine(number + " is even.");
      } else {
         Console.WriteLine(number + " is odd.");
      }
   }
}

The output of the above code is −

15 is odd.

for Loop

A for loop executes a block of statements multiple times with a controlled iteration pattern. It's ideal when you know the exact number of iterations needed.

Syntax

for (initialization; condition; increment) {
   statement(s);
}

Example

using System;

class Program {
   public static void Main() {
      Console.WriteLine("First 5 natural numbers:");
      
      for(int i = 1; i 

The output of the above code is −

First 5 natural numbers:
Number: 1
Number: 2
Number: 3
Number: 4
Number: 5


while Loop

A while loop repeats a block of statements as long as a specified condition remains true. The condition is evaluated before each iteration.

Syntax

while(condition) {
   statement(s);
}


Example

using System;

class Program {
   public static void Main() {
      int count = 1;
      
      Console.WriteLine("Countdown:");
      while(count 

The output of the above code is −

Countdown:
Count: 1
Count: 2
Count: 3
Loop finished!


do-while Loop

A do-while loop is similar to a while loop, but it evaluates the condition after executing the loop body. This ensures the loop executes at least once.

Syntax

do {
   statement(s);
} while(condition);


Example

using System;

class Program {
   public static void Main() {
      int num = 0;
      
      do {
         Console.WriteLine("Number: " + num);
         num++;
      } while(num 

The output of the above code is −

Number: 0
Number: 1
Number: 2
Loop completed!


Control Flow Comparison

Conclusion

Control statements are essential for creating dynamic C# programs that can make decisions and repeat operations. Understanding when to use conditional statements versus loops, and choosing between pre-test (while) and post-test (do-while) loops, enables you to write efficient and readable code that handles various programming scenarios effectively.