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What are Ref locals and Ref returns in C# 7.0?
A reference return value allows a method to return a reference to a variable, rather than a value.
The caller can then choose to treat the returned variable as if it were returned by value or by reference.
The caller can create a new variable that is itself a reference to the returned value, called a ref local.
In the below example even though we modify the color it doesn't have any mpact on the original array colors
Example
class Program{
public static void Main(){
var colors = new[] { "blue", "green", "yellow", "orange", "pink" };
string color = colors[3];
color = "Magenta";
System.Console.WriteLine(String.Join(" ", colors));
Console.ReadLine();
}
}Output
blue green yellow orange pink
To acheive this we can make use of ref locals
Example
public static void Main(){
var colors = new[] { "blue", "green", "yellow", "orange", "pink" };
ref string color = ref colors[3];
color = "Magenta";
System.Console.WriteLine(String.Join(" ", colors));
Console.ReadLine();
}Output
blue green yellow Magenta pink
Ref returns −
In the below example even though we modify the color it doesn't have any mpact on the original array colors
Example
class Program{
public static void Main(){
var colors = new[] { "blue", "green", "yellow", "orange", "pink" };
string color = GetColor(colors, 3);
color = "Magenta";
System.Console.WriteLine(String.Join(" ", colors));
Console.ReadLine();
}
public static string GetColor(string[] col, int index){
return col[index];
}
}Output
blue green yellow orange pink
Example
class Program{
public static void Main(){
var colors = new[] { "blue", "green", "yellow", "orange", "pink" };
ref string color = ref GetColor(colors, 3);
color = "Magenta";
System.Console.WriteLine(String.Join(" ", colors));
Console.ReadLine();
}
public static ref string GetColor(string[] col, int index){
return ref col[index];
}
}Output
blue green yellow Magenta pink
Updated on: 19-Aug-2020
488 Views
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