Regular Expression limiting match only for "." difficulties

I am developing a app for WP7 and using this for my RegEx

new System.Text.RegularExpressions.Regex(@"\D\.{1}");

Basically I want开发者_StackOverflow社区 user to input only numeric data with one . allowed for double, it works when user inputs only 1 period but app crashes as soon as another period is added

I would personally not use Regular Expressions for this.

bool isInputGood(string input) {
    double d;
    return double.TryParse(input, out d);
}

Of course, this won't reject something like 123.456.789, but it WILL accept something like 123.456 e+5

new System.Text.RegularExpressions.Regex(@"^\s*[0-9]+(\.[0-9]+)?\s*$");

This checks the whole string (anchored with ^ and $) and matches "legitimate" numbers.

Note that this is not a suitable check to be used in applications which may run on different regional settings, as the decimal separator may vary. Why not check the input by doing a double.TryParse() instead?