Strings: Padding Integers and Handling Decimal Float Numbers, C#

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//Title of this code
//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            // Ways to convert int to string            
            Console.WriteLine(3.ToString());
            Console.WriteLine(Convert.ToString(43).PadLeft(4,'0'));
            Console.WriteLine(43.ToString("D4"));
            Console.WriteLine(string.Format("{0:000}",45));
            Console.WriteLine();
            
            // converting float to string
            Console.WriteLine(3.35.ToString());
            Console.WriteLine(String.Format("{0} -> {1:0.00}", 123.45678, 123.45678)); // gives 2 decimal places
            Console.WriteLine(String.Format("{0} -> {1:0.00}", 123, 123)); // still gives 2 decimal places 123.00 even when there are no decimals
            
            Console.WriteLine();
            Console.WriteLine(string.Format("{0} -> {1:0.##}", 123.456, 123.456)); // gives 2 decimal places only when there are decimal digits
            Console.WriteLine(string.Format("{0} -> {1:0.##}", 123, 123)); // gives 123 without decimals because # denotes optional
            
            Console.WriteLine();
            // gives 123 without decimal places because after rounding to 2 decimals places result is 123.00
            Console.WriteLine(string.Format("{0} -> {1:0.##}", 123.001234, 123.001234)); 
            // gives 123.01 because after rounding last decimal point, 2 decimal places is not 123.00 any more
            Console.WriteLine(string.Format("{0} -> {1:0.##}", 123.007234, 123.007234)); 
            
            Console.WriteLine(string.Format("{0} -> {1:0.0#}", 123.00, 123.00)); // formats 1 mandatory decimal place, the other is optional
        }
    }
}

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Compilation time: 0.09 sec, absolute running time: 0.09 sec, cpu time: 0.08 sec, average memory usage: 16 Mb, average nr of threads: 4