Compound assignment operators in C#

Compound assignment operators in C# provide a shorter syntax to perform an operation and assign the result back to the same variable. These operators combine arithmetic, bitwise, or shift operations with assignment in a single step.

For example, x += 5 is equivalent to x = x + 5, but more concise and readable.

Syntax

The general syntax for compound assignment operators is −

variable operator= value;

This is equivalent to −

variable = variable operator value;

Types of Compound Assignment Operators

Using Arithmetic Assignment Operators

Example

using System;

class Program {
   public static void Main(string[] args) {
      int val = 7;
      Console.WriteLine("Initial value: " + val);

      val += 3;  // val = val + 3
      Console.WriteLine("After += 3: " + val);

      val -= 2;  // val = val - 2
      Console.WriteLine("After -= 2: " + val);

      val *= 7;  // val = val * 7
      Console.WriteLine("After *= 7: " + val);

      val /= 7;  // val = val / 7
      Console.WriteLine("After /= 7: " + val);

      val %= 5;  // val = val % 5
      Console.WriteLine("After %= 5: " + val);
   }
}

The output of the above code is −

Initial value: 7
After += 3: 10
After -= 2: 8
After *= 7: 56
After /= 7: 8
After %= 5: 3

Using Bitwise Assignment Operators

Example

using System;

class Program {
   public static void Main(string[] args) {
      int val = 12;  // Binary: 1100
      Console.WriteLine("Initial value: " + val + " (Binary: " + Convert.ToString(val, 2) + ")");

      val &= 9;  // val = val & 9 (Binary: 1001)
      Console.WriteLine("After &= 9: " + val + " (Binary: " + Convert.ToString(val, 2) + ")");

      val |= 6;  // val = val | 6 (Binary: 0110)
      Console.WriteLine("After |= 6: " + val + " (Binary: " + Convert.ToString(val, 2) + ")");

      val ^= 3;  // val = val ^ 3 (Binary: 0011)
      Console.WriteLine("After ^= 3: " + val + " (Binary: " + Convert.ToString(val, 2) + ")");

      val >= 3; // val = val >> 3 (shift right by 3)
      Console.WriteLine("After >>= 3: " + val + " (Binary: " + Convert.ToString(val, 2) + ")");
   }
}

The output of the above code is −

Initial value: 12 (Binary: 1100)
After &= 9: 8 (Binary: 1000)
After |= 6: 14 (Binary: 1110)
After ^= 3: 13 (Binary: 1101)
After >= 3: 6 (Binary: 110)

Using Compound Assignment with Strings

The += operator can also be used for string concatenation −

Example

using System;

class Program {
   public static void Main(string[] args) {
      string message = "Hello";
      Console.WriteLine("Initial: " + message);

      message += " World";  // message = message + " World"
      Console.WriteLine("After += ' World': " + message);

      message += "!";
      Console.WriteLine("After += '!': " + message);
   }
}

The output of the above code is −

Initial: Hello
After += ' World': Hello World
After += '!': Hello World!

Conclusion

Compound assignment operators in C# provide a concise way to perform operations and assign results simultaneously. They work with arithmetic operations, bitwise operations, shift operations, and even string concatenation, making code more readable and efficient.