regexes for parsing formatted numbers

Question

I am parsing documents which contain large amounts of formatted numbers, an example being:

 Frc consts  --     1.4362                 1.4362                 5.41         


        

Answer 1

You could start with this and go from there.

This regex matches all the numbers you've provided.
Unfortunatly, it also matches the 3 in 3 1.23-

// [-+]?(?:[0-9]+(?:\.[0-9]*)?|\.[0-9]+)(?:[eE][-+]?[0-9]+)?
// 
// Match a single character present in the list “-+” «[-+]?»
//    Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
// Match the regular expression below «(?:[0-9]+(?:\.[0-9]*)?|\.[0-9]+)»
//    Match either the regular expression below (attempting the next alternative only if this one fails) «[0-9]+(?:\.[0-9]*)?»
//       Match a single character in the range between “0” and “9” «[0-9]+»
//          Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
//       Match the regular expression below «(?:\.[0-9]*)?»
//          Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
//          Match the character “.” literally «\.»
//          Match a single character in the range between “0” and “9” «[0-9]*»
//             Between zero and unlimited times, as many times as possible, giving back as needed (greedy) «*»
//    Or match regular expression number 2 below (the entire group fails if this one fails to match) «\.[0-9]+»
//       Match the character “.” literally «\.»
//       Match a single character in the range between “0” and “9” «[0-9]+»
//          Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
// Match the regular expression below «(?:[eE][-+]?[0-9]+)?»
//    Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
//    Match a single character present in the list “eE” «[eE]»
//    Match a single character present in the list “-+” «[-+]?»
//       Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
//    Match a single character in the range between “0” and “9” «[0-9]+»
//       Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
Pattern regex = Pattern.compile("[-+]?(?:[0-9]+(?:\\.[0-9]*)?|\\.[0-9]+)(?:[eE][-+]?[0-9]+)?");
Matcher matcher = regex.matcher(document);
while (matcher.find()) {
    // matched text: matcher.group()
    // match start: matcher.start()
    // match end: matcher.end()
}