如何过滤掉字符串中的所有字母，但不是所有特殊字符

Question

I am writing a program for my Java class that is supposed to raise 2 to whatever power the user puts in and is to terminate when the user enters -1. The raising to the power and everything like that works, but the code I have to filter out letters also filters out special characters. Any suggestions?

Here is the code the filters out the characters:

inputString = inputString.replaceAll("[^\\d.]", "");

Answer 1

Try following code and let me know,

inputString = inputString.replaceAll("[^-?0-9]","");

The regex used is: [^-?0-9] which means:

replace any character other than - (minus) or digits . You don't have to worry about + sign