Something Strange happend in lua regexp,What's wrong with my script?

Question

Lua's regexp isn't compatible with Posix RegExp. For example, %d means \d which represents Number:0 to 9. And '%' is for escaping.

I want to match something like "180*180,512*512" which describe image size sequencies. In Posix mode,This regexp does work for me: ^(\d+\*\d+)(,\d+\*\d+)*$, And I changed this to Lua regexp mode: ^(%d+%*%d+)(,%d+%*%d+)*$, but it doesn't work. Here is my code

#!/usr/local/bin/lua

source = '96*96,180*180';
format = "^(%d+%*%d+)(,%d+%*%d+)*$";


if (not string.find(source, format)) then
    print 'wrong!'
else
    print 'ok!'
end

Answer 1

Lua does not have regex. It has its own patterns, as described in PiL.

For your particular case, you can simple replace the regex:

^(\d+\*\d+)(,\d+\*\d+)*$

to the following pattern:

^(%d+%*%d+)(,%d+%*%d+)$

Note that I removed the * after your second match-group, because Lua does not support it. You'll have to resort to using gmatch for capturing multiple groups:

local tMatches = {}
for sSize in str:gmatch "(%d+%*%d+)" do
    table.insert( tMatches, sSize )
end