Csharp/CSharp Tutorial/Language Basics/params

Array As Actual Param: params int[] inVals

<source lang="csharp">using System; class MainClass {

  public static void ListInts(params int[] inVals)
  {
     if (inVals != null)
        for (int i = 0; i < inVals.Length; i++)   
           inVals[i] = inVals[i] * 10;
  }
  static void Main()
  {
     int[] MyArr = new int[] { 5, 6, 7 };         
     ListInts(MyArr);                          
     foreach (int x in MyArr)
        Console.WriteLine("{0}", x);              
  }

}</source>

50
60
70

Demonstrate params

<source lang="csharp">using System;

class Min {

 public int minVal(params int[] nums) { 
   int m; 

   if(nums.Length == 0) { 
     Console.WriteLine("Error: no arguments."); 
     return 0; 
   } 

   m = nums[0]; 
   for(int i=1; i < nums.Length; i++)  
     if(nums[i] < m) m = nums[i]; 

   return m; 
 } 

}

class MainClass {

 public static void Main() { 
   Min ob = new Min(); 
   int min; 
   int a = 10, b = 20; 

   // call with two values 
   min = ob.minVal(a, b); 
   Console.WriteLine("Minimum is " + min); 

   // call with 3 values 
   min = ob.minVal(a, b, -1); 
   Console.WriteLine("Minimum is " + min); 

   // call with 5 values 
   min = ob.minVal(18, 23, 3, 14, 25); 
   Console.WriteLine("Minimum is " + min); 

   // can call with an int array, too 
   int[] args = { 45, 67, 34, 9, 112, 8 }; 
   min = ob.minVal(args); 
   Console.WriteLine("Minimum is " + min); 
 } 

}</source>

Minimum is 10
Minimum is -1
Minimum is 3
Minimum is 8

Mix params array type with other data types

<source lang="csharp">using System; class MainClass {

 public static void ArrayOfInts(string msg, params int[] list) 
 {
   Console.WriteLine(msg);
   for ( int i = 0 ; i < list.Length ; i++ )
     Console.WriteLine(list[i]);
   Console.WriteLine();
 }
 public static void Main() 
 {
   int[] intArray = new int[3] {10,11,12};
   ArrayOfInts("Here is an array of ints", intArray);
   ArrayOfInts("Enjoy these 3 ints", 1, 2, 3);
   ArrayOfInts("Take some more!", 55, 4, 983, 10432, 98, 33);
 }

}</source>

Here is an array of ints
10
11
12
Enjoy these 3 ints
1
2
3
Take some more!
55
4
983
10432
98
33

Sending in args using params keyword: object, int and string

<source lang="csharp">using System; class Person {

 public string fullName;
 public int age;
 public Person(string n, int a)
 {
   fullName = n;
   age = a;
 }
 public void PrintInfo()
 {
   Console.WriteLine("{0} is {1} years old", fullName, age);
 }

} class MainClass {

 public static void ArrayOfObjects(params object[] list) 
 {
   for ( int i = 0 ; i < list.Length ; i++ )
   {   
     if(list[i] is Person)
     {
       ((Person)list[i]).PrintInfo();
     }
     else
       Console.WriteLine(list[i]);
   }
   Console.WriteLine();
 }
 public static void Main() 
 {
   Person p = new Person("Fred", 93);
   ArrayOfObjects(7, p, "System.String"); 
 }

}</source>

7
Fred is 93 years old
System.String

Use "params int[]"

<source lang="csharp">using System; class MainClass {

  static void Main() {
     int first = 5, second = 6, third = 7;
     ListInts(first, second, third);
     Console.WriteLine("{0}, {1}, {2}", first, second, third);
  }
  public static void ListInts(params int[] inVals)
  {
     for (int i = 0; i < inVals.Length; i++)        
     {
        inVals[i] = inVals[i] * 10;
        Console.WriteLine("{0} ", inVals[i]);       
     }
  }
  

}</source>

50
60
70
5, 6, 7

Use regular parameter with a params parameter.

<source lang="csharp">using System;

class MyClass {

 public void showArgs(string msg, params int[] nums) { 
   Console.Write(msg + ": "); 

   foreach(int i in nums) 
     Console.Write(i + " "); 

   Console.WriteLine(); 
 } 

}

class MainClass {

 public static void Main() { 
   MyClass ob = new MyClass(); 

   ob.showArgs("Here are some integers",  
               1, 2, 3, 4, 5); 

   ob.showArgs("Here are two more",  
               17, 20); 

 } 

}</source>

Here are some integers: 1 2 3 4 5
Here are two more: 17 20