Padding zeros with custom numeric format strings in C#

format_int.cs

var x = 4;
var y = x.ToString(); // y equals "4"

var x = 4;
var y = x.ToString("##"); // y equals "4"

var x = 4;
var y = x.ToString("###"); // y equals "4"

var x = 4;
var y = x.ToString("0#"); // y equals "04"

var x = 4;
var y = x.ToString("00#"); // y equals "004"

var x = 14;
var y = x.ToString("00#"); // y equals "014"

var x = 214;
var y = x.ToString("00#"); // y equals "214"

var x = 3214;
var y = x.ToString("00#"); // y equals "3214"

// Learn more: https://docs.microsoft.com/en-us/dotnet/standard/base-types/custom-numeric-format-strings