Params

 

  • Params was introduced in C# 1.0
    params parameters have allowed developers to declare methods that accept a variable number of arguments, passed as an array. This feature simplifies method calls when the number of arguments is unknown at compile time
  • Single params per method: Only one params parameter in a method is allowed to avoid ambiguity. We need to specify the array type, and all arguments passed must be compatible with that type.
  • Params must be the last parameter: The params keyword should be the last parameter in the method signature to ensure that the method correctly interprets the arguments.
  • Empty array: If no arguments are passed to a params parameter, it will be treated as an empty array.
  • Only one Params keyword is allowed and no additional Params will be allowed in function declaration after a params keyword.
  • Simplifies Method Overloading,Code Readability is improved.

 

				
					
using System.Threading.Channels;

var calculate = new Calculate();


//without params
calculate.SimpleCalculate(1, 2, 3 );//without params...method overload
calculate.SimpleCalculate(1, 2, 3 ,4);//without params...method overload

//Collection expression - without  params
calculate.SimpleCalculateCollectionExpression(new int[] { 1, 2, 3 }); //without collection expression...
calculate.SimpleCalculateCollectionExpression([1, 2, 3]); //with collection expression....c#12...

//with params...
calculate.SimpleCalculateParams(new int[] { 1, 2, 3 });
calculate.SimpleCalculateParams([1, 2, 3 ]);
calculate.SimpleCalculateParams(1, 2, 3 );

//what was not working before c#13 ??? This was not compiling......
//so before c#13 it worked only for arrays, but now it can work for any collection type..
calculate.SimpleCalculateParamsBeforeCsharp13(1, 2, 3);


/*-------------------------ANOTHER EXAMPLE---------------------------------------------------------*/
//This takes example of params with list of employees..which was not working earlier...now it works..

var emp = new EmployeeSalary();
emp.CalculateSalary([new Employee() { Salary = 1000 }, new Employee() { Salary = 2000 }]);
emp.CalculateSalary(new Employee() { Salary = 1000 }, new Employee() { Salary = 2000 });

/*-----------------------------------------------------------------------------------*/


public class Calculate
{
    public void SimpleCalculate(int a, int b, int c) => Console.WriteLine(a + b + c);
    public void SimpleCalculate(int a, int b, int c, int d) => Console.WriteLine(a + b + c + d);
    public void SimpleCalculateParams(params int[] numbers) => Console.WriteLine(numbers.Sum());
    public void SimpleCalculateCollectionExpression(int[] numbers) => Console.WriteLine(numbers.Sum());

    public void SimpleCalculateParamsBeforeCsharp13(params List<int> numbers) => Console.WriteLine(numbers.Sum());
}

public class EmployeeSalary
{
    //public void CalculateSalary(params Employee[] employees)
    //{
        
    //}

    /*----------works for list as well---------*/
    public void CalculateSalary(params List<Employee> employees)
    {
        Console.WriteLine(employees.Sum(emp => emp.Salary));
    }

    //public void CalculateSalary(params Span<Employee> employees)
    //{
    //    //Console.WriteLine(employees.Sum(emp => emp.Salary));
    //    foreach (var item in employees)
    //    {
    //        Console.WriteLine(item.Salary);
    //    }
    //}

}

public class Employee
{
    public string? Id { get; set; }
    public int Salary { get; set; }
}

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