How to split string if splitting character is dynamic or unknown?

Question

I want to make a Java program in which I want to take a String as a input. The string will have two integer numbers and operation to be performed. eg. 25+85 or 15*78

The output will the solution of the string.

But I don't know how to split the string because operator sign is not known before execution.

Answer 1

You would want to check what operation it is using by using String.contains("+"); and checking all the other operators you want to support. Then split wherever that operator is, String.split("+") . From there parse the output of String.split("+") by using Integer.parseInt(String s) and then return the sum. Pretty simple, good luck.

Answer 2

You can use the split() method of the String class to split the input at non-digit characters:

input.split("\\D");

This will give you an array containing only the numbers. I guess you also want to get the operator somehow? Although it's not the most elegant way, you might want to start with input.replaceAll("[^\\\\*\\\\+\\\\-\\\\/]", "") to remove everything that's not an operator, but you will still have to do some careful input filtering. What if i type 5+4*6 oder 2+hello ?