Why does the following code does not match? the expression is not that difficult and online regex tester also state that it should work. Am i doing something wrong with the escapes?
QRegExp rex("(.*?)(\\d+\\.\\d+)_(\\d+\\.\\d+).*?");
QString fileName("tile_10.0000_47.3100_0.1_.dat");
if (rex.indexIn(fileName)>=0) {
// ...
}
QRegExp does not support lazy quantifiers, so *? does not work here. Also, the .*? at the end of the pattern does not match any text, it can safely be removed.
I suggest replacing the first .*? with ([^_]*)_ pattern (0+ chars other than _ and a _ right after them) to get to the first digits.digits text:
rex("([^_]*)_(\\d+\\.\\d+)_(\\d+\\.\\d+)")
Or, if you need to match the data from the start of the string, prepend the pattern with ^ (start of string).
One possile change could be:
(.*?)(\d+\.\d+)_(\d+\.\d+)_(\d+\.\d+)_\..*
Which is very strict to your example.
And here one which accepts any sequence of numbers followed by underscores till file extension.
(.*?)((\d+\.\d+)_+)\..*
Hope that helps
You can also change quantifiers behaviour with QRegExp.setMinimal() to make them non-greedy by default and with a little change to your pattern:
QRegExp rex("(.*)(\\d+\\.\\d+)_(\\d+\\.\\d+)(\\D.*|$)");
rex.setMinimal(true);
