What are integer literals in C#?

An integer literal in C# is a constant numeric value written directly in the code. Integer literals can be decimal (base 10) or hexadecimal (base 16) constants. A prefix specifies the base: 0x or 0X for hexadecimal, with no prefix for decimal. They can also have suffixes like U for unsigned and L for long.

Syntax

Following is the syntax for different types of integer literals −

// Decimal literals
123
200L    // long
456U    // unsigned int
789UL   // unsigned long

// Hexadecimal literals
0xFF    // 255 in decimal
0x1A    // 26 in decimal
0X2BL   // long hexadecimal

Types of Integer Literals

Using Decimal Integer Literals

Decimal literals are the most common type, written without any prefix −

using System;

class Program {
   static void Main(string[] args) {
      // Different decimal integer literals
      int a = 200;
      uint b = 90u;
      long c = 300L;
      ulong d = 400UL;
      
      Console.WriteLine("int: " + a);
      Console.WriteLine("unsigned int: " + b);
      Console.WriteLine("long: " + c);
      Console.WriteLine("unsigned long: " + d);
   }
}

The output of the above code is −

int: 200
unsigned int: 90
long: 300
unsigned long: 400

Using Hexadecimal Integer Literals

Hexadecimal literals start with 0x or 0X prefix and use digits 0-9 and letters A-F −

using System;

class Program {
   static void Main(string[] args) {
      // Hexadecimal integer literals
      int hex1 = 0xFF;        // 255 in decimal
      int hex2 = 0x1A;        // 26 in decimal
      long hex3 = 0x2BL;      // 43 in decimal
      uint hex4 = 0xABCDu;    // 43981 in decimal
      
      Console.WriteLine("0xFF = " + hex1);
      Console.WriteLine("0x1A = " + hex2);
      Console.WriteLine("0x2BL = " + hex3);
      Console.WriteLine("0xABCDu = " + hex4);
   }
}

The output of the above code is −

0xFF = 255
0x1A = 26
0x2BL = 43
0xABCDu = 43981

Binary Literals (C# 7.0+)

Starting with C# 7.0, you can also use binary literals with the 0b prefix −

using System;

class Program {
   static void Main(string[] args) {
      // Binary integer literals (C# 7.0+)
      int binary1 = 0b1010;      // 10 in decimal
      int binary2 = 0b11110000;  // 240 in decimal
      
      Console.WriteLine("0b1010 = " + binary1);
      Console.WriteLine("0b11110000 = " + binary2);
   }
}

The output of the above code is −

0b1010 = 10
0b11110000 = 240

Conclusion

Integer literals in C# provide a flexible way to represent constant numeric values in decimal, hexadecimal, or binary formats. They support various suffixes to specify the exact integer type needed, making them essential for precise numeric programming and memory-efficient code.