C# | Params

Params is an important keyword in C#. It is used as a parameter which can take the variable number of arguments.

Important Point About Params Keyword :

• It is useful when programmer don’t have any prior knowledge about the number of parameters to be used.
• Only one Params keyword is allowed and no additional Params will be allowed in function declaration after a params keyword.
• The length of params will be zero if no arguments will be passed.

Examples: To illustrate the use of params keyword

• Simple program to show the params keyword usage

  // C# program to illustrate the
  // use of params keyword
  using System;
  namespace Examples {
  
  class Geeks {
  
      // function containing params parameters
      public static int Add(params int[] ListNumbers)
      {
          int total = 0;
  
          // foreach loop
          foreach(int i in ListNumbers)
          {
              total += i;
          }
          return total;
      }
  
  // Driver Code
  static void Main(string[] args)
  {
  
      // Calling function by passing 5
      // arguments as follows
      int y = Add(12,13,10,15,56);
  
      // Displaying result
      Console.WriteLine(y);
  }
  }
  }

  Output :

  
  
  

  106
  

  Explanation : There is no need to define the size of the array because using params keyword in above program, the Integer data will be in the form:
  ListNumbers
  [0] 12
  [1] 13
  [2] 10
  [3] 15
  [4] 56

• Object type Params will allow any type of arguments and any number of arguments as follows :

  // C# program to illustrate the
  // use of object type params
  using System;
  
  namespace Example2 {
  class Geeks {
  
          // function using object type params
          public void result(params object[] array)
          {
              for (int i = 0; i < array.Length; i++)
              {
  
                  // Display result
                  Console.WriteLine(array[i]);
              }
          }
  
      // Driver Code
      static void Main(string[] args)
      {
          Geeks gfg = new Geeks();
  
          // Variable length arguments
          gfg.result("Geeks", "GFG",
                     "ProGeek Cup 2.0",
                          "G4G", "100");
      }
  
  }
  }

  Output :

  Geeks
  GFG
  ProGeek Cup 2.0
  G4G
  100
  

  Explanation : In above program the object type params parameter can accept any type of data and any number of arguments.