Regex for numbers only

Solution 1:

Use the beginning and end anchors.

Regex regex = new Regex(@"^\d$");

Use "^\d+$" if you need to match more than one digit.

Note that "\d" will match [0-9] and other digit characters like the Eastern Arabic numerals ٠١٢٣٤٥٦٧٨٩. Use "^[0-9]+$" to restrict matches to just the Arabic numerals 0 - 9.

If you need to include any numeric representations other than just digits (like decimal values for starters), then see @tchrist's comprehensive guide to parsing numbers with regular expressions.

Solution 2:

Your regex will match anything that contains a number, you want to use anchors to match the whole string and then match one or more numbers:

regex = new Regex("^[0-9]+$");

The ^ will anchor the beginning of the string, the $ will anchor the end of the string, and the + will match one or more of what precedes it (a number in this case).

Solution 3:

If you need to tolerate decimal point and thousand marker

var regex = new Regex(@"^-?[0-9][0-9,\.]+$");

You will need a "-", if the number can go negative.

Solution 4:

It is matching because it is finding "a match" not a match of the full string. You can fix this by changing your regexp to specifically look for the beginning and end of the string.

^\d+$

Solution 5:

Perhaps my method will help you.

    public static bool IsNumber(string s)
    {
        return s.All(char.IsDigit);
    }