Unable to match this string “18% on $25.56” with this regex “.*(\d+)%.*\$(\d+)(\.\d+)?$”. What am I doing wrong?

Question

I'm trying to get the numbers out of a string that user inputs for calculating tip. The query could be "Calculate 18% tip on $25.56" or simply "18% $25.56"

I've built up this regex

.*(\d+)%.*\$(\d+)(\.\d+)?$

However, the first capturing group doesn't capture 18, just 8. What am I doing wrong ?

EDIT: Based on the answer below, I made my regex more error resilient. For matching a string like this

"Calculate18sdaasa%onasda$dsada25dasda.56aaddsadas dsad asdadas 18 sadasd 23 asdasd .56 asdasd"

I now have the regex as

.*?(\\d+).*?%.*?\\$.*?(\\d+).*?(\\.\\d+).*

This captures the first three numbers 18, 25 and .56 which is what I need.

Answer 1

Note that .* in the beginning of your RegEx is greedy, and that (\\d+) will also be satisfied with only matching a single-digit number. Thus, the starting .* kind of "steals" all but the last digit of your first number while (\\d+) still matches the last digit of the first number.

Do it like this instead:

.*?(\d+)%.*\$(\d+)(\.\d+)?$

.*? is non-greedy, that means, it will match as few characters as possible to satisfy the pattern.

Answer 2

尝试以下正则表达式模式：

\d+.?\d+