Csharp/CSharp Tutorial/Language Basics/out

Out Parameters

using System;
class Point
{
    public Point(int x, int y)
    {
        this.x = x;
        this.y = y;
    }
    
    public void GetPoint(out int x, out int y)
    {
        x = this.x;
        y = this.y;
    }
    
    int x;
    int y;
}
class MainClass
{
    public static void Main()
    {
        Point myPoint = new Point(10, 15);
        int x;
        int y;
        
        myPoint.GetPoint(out x, out y);
        Console.WriteLine("myPoint({0}, {1})", x, y);
    }
}

myPoint(10, 15)

Ref and Out Parameters

using System;
class Point
{
    public Point(int x, int y)
    {
        this.x = x;
        this.y = y;
    }
    
    public void GetPoint(ref int x, ref int y)
    {
        x = this.x;
        y = this.y;
    }
    
    int x;
    int y;
}
class MainClass
{
    public static void Main()
    {
        Point myPoint = new Point(10, 15);
        int x = 0;
        int y = 0;
        
        myPoint.GetPoint(ref x, ref y);
        Console.WriteLine("myPoint({0}, {1})", x, y);
    }
}

myPoint(10, 15)

Use out

using System; 
 
class Decompose { 
 
  public int parts(double n, out double frac) { 
    int whole; 
 
    whole = (int) n; 
    frac = n - whole; // pass fractional part back through frac 
    return whole; // return integer portion 
  } 
} 
  
class MainClass { 
  public static void Main() {   
   Decompose ob = new Decompose(); 
    int i; 
    double f; 
 
    i = ob.parts(10.125, out f); 
 
    Console.WriteLine("Integer portion is " + i); 
    Console.WriteLine("Fractional part is " + f); 
  } 
}

Integer portion is 10
Fractional part is 0.125

Use "out" keyword (no need to assign because it is an out)

1. An out parameter is used to pass a value out of a method.
2. It is not necessary to give the variable used as an out parameter an initial value.
3. An out parameter is always considered unassigned.
4. The method must assign the parameter a value prior to the method"s termination.

using System;
class MainClass
{
  public static void Add(int x,int y, out int ans)
  {
    ans = x + y;
  }
  public static void Main() 
  {
    
    Console.WriteLine("Adding 2 ints using out keyword");
    int ans;
    Add(90, 90, out ans);
    Console.WriteLine("90 + 90 = {0}\n", ans);
  }
}

Adding 2 ints using out keyword
90 + 90 = 180

Use two out parameters

using System; 
 
class Num { 
   
  public bool hasComFactor(int x, int y,out int least, out int greatest) { 
    least = 1; 
    greatest = 1;  
 
    if(least != 1) 
       return true; 
    else 
       return false; 
  } 
} 
  
class MainClass { 
  public static void Main() {   
    Num ob = new Num(); 
    int lcf, gcf; 
 
    if(ob.hasComFactor(231, 105, out lcf, out gcf)) { 
      Console.WriteLine("Lcf of 231 and 105 is " + lcf); 
      Console.WriteLine("Gcf of 231 and 105 is " + gcf); 
    } 
    else 
      Console.WriteLine("No common factor for 35 and 49."); 
 
    if(ob.hasComFactor(35, 51, out lcf, out gcf)) { 
      Console.WriteLine("Lcf of 35 and 51 " + lcf); 
      Console.WriteLine("Gcf of 35 and 51 is " + gcf); 
    } 
    else 
      Console.WriteLine("No common factor for 35 and 51."); 
 
  } 
}

No common factor for 35 and 49.
No common factor for 35 and 51.