C# Method/function Concepts and Advanced Features

  • Why

    • Suppose we want to calculate sum of two number say a, b we can implement by direct implementation like a + b.

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      var a = 7;
var b = 50;
var c = a+b;

    • Now Take The Cases

      • number should be positive
      • Maxium value of number cant be greater than 100
      • Sum of Both number should be less than 100 and greater than 30
      • ans aso on.
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      var a = 7;
var b = 50;
if (a>0 && b>0)
{
    if(Math.Max(a,b)<100)
    {
        var c = a+b;
        if(c<100 && c>=30)
        {
            Console.WriteLine($"Sum Of Number is {c}");
        }
        else
        {
            Console.WriteLine("Sum of Both number should be less than 100 and greater than 30");
        }
    }
    else
    {
        Console.WriteLine("Number Should Be less Than 100");
    }
}
else
{
    Console.WriteLine("Number Should Be Positive");
}

    • Imagine this validation is require in more than one place then our code will be Explode Exponentially

    • It Will be Hard TO Main tain Also

    • To Solve this Issue We Use Function. Like this for Above example

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      public string Sum(int a, int b)
{
    if (a>0 && b>0)
    {
        if(Math.Max(a,b)<100)
        {
            var c = a+b;
            if(c<100 && c>=30)
            {
               return $"Sum Of Number is {c}";
            }
            else
            {
                 return "Sum of Both number should be less than 100 and greater than 30";
            }
        }
        else
        {
             return  "Number Should Be less Than 100";
        }
    }
    else
    {
         return "Number Should Be Positive";
    }
}

    • More Detailed Explanation Below With Different Cases And Example

Return Type

A method can return a value. The return type of the method must be specified. it dosen’t return any value than void is used

Example: Return Type

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int Add(int a, int b)
{
    return a + b;
}

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void Add(int a, int b)
{
    Console.WriteLine( a + b);
}

Parameters

Methods can take parameters to perform operations with input values.

Example: Parameters

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void Greet(string name)
{
    Console.WriteLine("Hello, " + name);
}

Default Parameters

Methods can have default parameters, which are used if no arguments are provided when the method is called.

Example: Default Parameters

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void GreetWithDefault(string name = "Guest")
{
    Console.WriteLine("Hello, " + name);
}

Method Overloading

Method overloading allows multiple methods with the same name but different parameters.

Example: Method Overloading

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int Add(int a, int b)
{
    return a + b;
}

double Add(double a, double b)
{
    return a + b;
}

Optional Parameters

Optional parameters have default values and can be omitted when the method is called.

Example: Optional Parameters

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void PrintName(string firstName, string lastName = "")
{
    Console.WriteLine(firstName + " " + lastName);
}

More Adavanced

Ref and Out Parameters

The ref and out keywords allow passing parameters by reference or returning multiple values.

Example: Ref and Out Parameters

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void Modify(ref int number)
{
    number += 10; // Modify the original value
}

void Retrieve(out int number)
{
    number = 42; // Assign a value to the out parameter
}

Lambda Expressions

Lambda expressions provide a concise way to define anonymous methods using the => syntax.

Example: Lambda Expressions

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Func<int, int, int> add = (a, b) => a + b;

Delegate Methods

Delegates are types that represent references to methods. They are used to pass methods as arguments to other methods.

Example: Delegate Methods

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delegate int MathOperation(int a, int b);
MathOperation add = (a, b) => a + b;

Async Methods

Asynchronous methods allow operations to run asynchronously, improving performance for I/O-bound operations.

Example: Async Methods

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async Task<int> GetDataAsync()
{
    // Asynchronous operations
    return await SomeAsyncOperation();
}

Extension Methods

Extension methods allow you to add new methods to existing types without modifying the original type.

Example: Extension Methods

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public static class StringExtensions
{
    public static bool IsNullOrEmpty(this string str)
    {
        return string.IsNullOrEmpty(str);
    }
}

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