Random.Next() Method in C#

The Random.Next() method in C# is used to generate non-negative random integers. It provides multiple overloads to control the range of generated numbers, making it useful for various scenarios like games, simulations, and testing.

Syntax

The Random.Next() method has three overloads −

public virtual int Next();
public virtual int Next(int maxValue);
public virtual int Next(int minValue, int maxValue);

Parameters

• maxValue − The exclusive upper bound of the random number (0 to maxValue-1).

• minValue − The inclusive lower bound of the random number.

• maxValue − The exclusive upper bound of the random number (minValue to maxValue-1).

Return Value

Returns a 32-bit signed integer greater than or equal to 0 and less than Int32.MaxValue for the parameterless version, or within the specified range for other overloads.

Using Random.Next() Without Parameters

This overload generates random integers from 0 to Int32.MaxValue −

using System;

public class Demo {
   public static void Main() {
      Random r = new Random();
      Console.WriteLine("Random numbers.....");
      for (int i = 1; i <= 5; i++)
         Console.WriteLine(r.Next());
   }
}

The output of the above code is −

Random numbers.....
1014639030
1510161246
1783253715
487417801
249480649

Using Random.Next() with Maximum Value

This overload generates random integers from 0 to the specified maximum value (exclusive) −

using System;

public class Demo {
   public static void Main() {
      Random r = new Random();
      Console.WriteLine("Random numbers from 0 to 9.....");
      for (int i = 1; i <= 5; i++)
         Console.WriteLine(r.Next(10));
         
      Console.WriteLine("\nRandom numbers from 0 to 99.....");
      for (int i = 1; i <= 3; i++)
         Console.WriteLine(r.Next(100));
   }
}

The output of the above code is −

Random numbers from 0 to 9.....
2
7
8
5
9

Random numbers from 0 to 99.....
43
76
21

Using Random.Next() with Range

This overload generates random integers within a specified range using minimum and maximum values −

using System;

public class Demo {
   public static void Main() {
      Random r = new Random();
      Console.WriteLine("Random numbers from 10 to 20.....");
      for (int i = 1; i <= 5; i++)
         Console.WriteLine(r.Next(10, 21));
         
      Console.WriteLine("\nRandom numbers from 50 to 59.....");
      for (int i = 1; i <= 3; i++)
         Console.WriteLine(r.Next(50, 60));
   }
}

The output of the above code is −

Random numbers from 10 to 20.....
15
18
12
20
11

Random numbers from 50 to 59.....
54
57
52

Common Use Cases

Conclusion

The Random.Next() method provides flexible random integer generation with three overloads for different scenarios. Use the parameterless version for large ranges, specify a maximum for bounded ranges, or use both minimum and maximum parameters for custom ranges where the maximum value is always exclusive.