我的Regex表达式有什么问题

Question

I have a written a Regex to check whether the string consists of 9 digits or not as follows but this always returning me false even if I have my string as 123456789 .

if (Regex.IsMatch(strSSN, " ^\\d{9}$"))

Can any one tell what's wrong and also if any better one provide me .. What i am achieving is the string should have only numeric data and the length should be =9

Answer 1

Spaces are significant in regular expressions (and of course, you can't match a space character before the start of the string). Remove it and everything should be fine:

if (Regex.IsMatch(strSSN, "^\\d{9}$"))

Also, you generally want to use verbatim strings for regexes in C#, so you don't have to double your backslashes, but this is just a convenience, not the reason for your problem:

if (Regex.IsMatch(strSSN, @"^\d{9}$"))

Answer 2

this should work

^\d{9}$

hope that helps

Answer 3

您在"和^之间有一个空格，应该为：

if (Regex.IsMatch(strSSN, "^\\d{9}$"))

Answer 4

could it be the space at the beginning of your pattern? That seems wierd, a space then a number anchored to the start of the line.

This should give you what you want:

if (Regex.IsMatch(strSSN, "^\\d{9}$"))