How to pad left a number with a specific amount of zeroes
C# has the built-in PadLeft() function for this: someString = someString.PadLeft(8, ‘0’); And here’s an article on it at Microsoft Learn. To use a regular expression, do something like this: string someText = “asd 123 rete”; someText = Regex.Replace(someText, @”\d+”, n => n.Value.PadLeft(8, ‘0’));