C# Online Compiler | .NET Fiddle

using System;
using System.Text;
					
public class Program
{
	// How many ways can you write to reverse a string in C#?
	
	public static void Main()
	{
		string str = "I am in Coffs harbour";
		
		Console.WriteLine(str.Reverse());
		Console.WriteLine(str.Reverse2());
		Console.WriteLine(str.Reverse3());
	}
}

public static class StringEx
{
	public static string Reverse(this string str)
	{	
		int strLen = str.Length;
		char[] arr = new char[strLen];
		int arrIndex = 0;
		for (int i = strLen - 1; i >= 0; i--)
		{
			arr[arrIndex++] = str[i];
		}
		
		return new string(arr);
	}
	
	public static string Reverse2(this string str)
	{
		StringBuilder b = new StringBuilder();
		
		for (int i = str.Length - 1; i >= 0; i--)
		{
			b.Append(str[i]);	
		}
		
		return b.ToString();
	}
	
	public static string Reverse3(this string str)
	{
		var arr = str.ToCharArray();
		Array.Reverse(arr);
		return new string(arr);
	}
}

 
using System;
using System.Text;
                    
public class Program
{
    // How many ways can you write to reverse a string in C#?
    
    public static void Main()
    {
        string str = "I am in Coffs harbour";
        
        Console.WriteLine(str.Reverse());
        Console.WriteLine(str.Reverse2());
        Console.WriteLine(str.Reverse3());
    }
}
​
public static class StringEx
{
    public static string Reverse(this string str)
    {   
        int strLen = str.Length;
        char[] arr = new char[strLen];
        int arrIndex = 0;

Cached Result

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    Esta função é para obtermos a soma de todos os numeros impares inferiores a ele
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