Regular Expression Example

^[0-9]+:

This will look for at the start of each line something like 1:

It's very useful to reformat some java codes which were posted with line number.

Regular Expression in TextPad

Link

Configure -> Preferences -> Editor
Check "Use POSIX regular expression syntax"

search c.+b
all the following will be found:
c234b
cxyz123b
C123-=b

Search .+=
means anything until=

Special character which needs escaping \

+ ? . * ^ () [] {} | \

. is wildcard
[blabla]
example: [0-9] [a-z]
[^0-9] means non digits
^PATTERN: find pattern at start of line
PATTERN$: find pattern at end of line
for example, search ^todo find line 1, search todo$ find line2.
line 1: todo things
line 2: we will do it. todo

for example,
search c.*b, find 1,2, and 3.
search c.+b, find 2 and 3.
search c.?b, find 1 and 2.
search c.\{3\}b, find 3
search cx\{3\}b, find 3 too

1 cb
2 cab
3 cxxxb

Quantifiers:

+      1 or more times

?      0 or 1 time; item is optional

*      0 or more times; item is optional or repeatable

{N}    N times

{N,}   N or more times

{N,M}  N to M times