How to do it...

For meeting the mentioned requirement, proceed as follows:

How it works...

The solution is based on searching all non-digit characters in the string and replacing them with blank. The negated operator (^) is used within the box brackets and the \d denotes the digits. We have used all occurrences, as this will replace all non-digits.

Suppose the user enters the number having + and parentheses and blank spaces.

This will remove all special characters, as well as spaces, and will only display numbers.

There's more...

Alternately, you may also use [0-9] in place of \d. The regex will be then be written as '[^0-9]'. In addition, it is important to include regex in the replace statement. Otherwise, instead of searching the pattern within the text, the system searches for [^\d] or [^0-9] in the text, and the desired results will not be achieved.