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POHow do I make a regex match for measurement units?
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copied!<p>I'm building a small Java library which has to match units in strings. For example, if I have "300000000 m/s^2", I want it to match against "m" and "s^2".</p> <p>So far, I have tried most imaginable (by me) configurations resembling (I hope it's a good start)</p> <pre><code>"[[a-zA-Z]+[\\^[\\-]?[0-9]+]?]+" </code></pre> <p>To clarify, I need something that will match <code>letters[^[-]numbers]</code> (where [ ] denotes non obligatory parts). That means: letters, possibly followed by an exponent which is possibly negative.</p> <p>I have studied regex a little bit, but I'm really not fluent, so any help will be greatly appreciated!</p> <p>Thank you very much,</p> <p><strong>EDIT:</strong> I have just tried the first 3 replies</p> <pre><code>String regex1 = "([a-zA-Z]+)(?:\\^(-?\\d+))?"; String regex2 = "[a-zA-Z]+(\\^-?[0-9]+)?"; String regex3 = "[a-zA-Z]+(?:\\^-?[0-9]+)?"; </code></pre> <p>and it doesn't work... I know the code which tests the patterns work, because if I try something simple, like matching "[0-9]+" in "12345", it will match the whole string. So, I don't get what's still wrong. I'm trying with changing my brackets for parenthesis where needed at the moment...</p> <p><strong>CODE USED TO TEST:</strong></p> <pre><code>public static void main(String[] args) { String input = "30000 m/s^2"; // String input = "35345"; String regex1 = "([a-zA-Z]+)(?:\\^(-?\\d+))?"; String regex2 = "[a-zA-Z]+(\\^-?[0-9]+)?"; String regex3 = "[a-zA-Z]+(?:\\^-?[0-9]+)?"; String regex10 = "[0-9]+"; String regex = "([a-zA-Z]+)(?:\\^\\-?[0-9]+)?"; Pattern pattern = Pattern.compile(regex3); Matcher matcher = pattern.matcher(input); if (matcher.matches()) { System.out.println("MATCHES"); do { int start = matcher.start(); int end = matcher.end(); // System.out.println(start + " " + end); System.out.println(input.substring(start, end)); } while (matcher.find()); } } </code></pre>

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