trouble with C# and regular expressions

Question

Hi I am trying to use regular expression to check if a string is a number and I do not want leading zeros so 123 is legal but 0123 is not and I am using the following: Regex objNaturalPattern = new Regex([1-9][0-9]*); This works fine detecting if it is a number or alpha but it always gives me true for leading zeros how can I make the zeros in front give me a false? Thanks

Bjarni · Answer

Thanks that worked but now I have another question if I want the string that I am testing to be of a certain length how does that work I was trying: Regex regex = new Regex(^[1-9][0-9]{05}); where {05} should allow the string to be 0 to 5 digits long but that does not work for me. Any ideas. Does anyone know of a good place to read about C# regex. It seems to me that diffrent characters have diffrent meaning in different programming languages. BR

Mike Gold · Answer

try Regex exp = new Regex ( ^[1-9][0-9]* );