Why is the following regex not working in C using regcomp

Question

I have the following regex to match the last pair of braces in a string,

.+(?={)(.+)(?=})

The example string is,

abc{abc=bcd}{gef=hij}

I want the contents within the last braces (gef=hij) inside the captured group. This works in a regex tester available in the web

When I use regcomp to compile the same regex, it doesnt. Any ideas?

int reti = regcomp(&regex, ".+(?={)(.+)(?=})", REG_EXTENDED);
if (reti) {
    fprintf(stderr, "Could not compile regex\n");
    exit(1);
}

Which language are you running? – Avinash Raj Nov 28 '14 at 12:11 — Avinash Raj, Nov 28 '14 at 12:11

Avinash Raj · Accepted Answer · 2014-11-28T12:53:14.133

1

Anyway, regcomp uses POSIX BRE or ERE, which doesn't support look-ahead or look-behind.

.+{(.+)}

Grab the string you want from group index 1.

edited Nov 28 '14 at 12:53

answered Nov 28 '14 at 12:13

Avinash Raj

Still fails to compile using regcomp – Karthik H Nov 28 '14 at 12:21
did you try this `.+{(.+)}` ? Which lang are you running? – Avinash Raj Nov 28 '14 at 12:24
Hi Avinash, All your solutions are correct, but to compile them using regcomp the parentheses(for grouping) need to be replaced with square brackets. Then they compile just fine. Please change and I will accept your answer. I am using C – Karthik H Nov 28 '14 at 12:27
@KarthikH i don't know what you mean. Click this http://stackoverflow.com/posts/27188435/edit and edit my answer. – Avinash Raj Nov 28 '14 at 12:31
I don't think regcomp supports look-behind, since it uses ERE or BRE. – nhahtdh Nov 28 '14 at 12:45
thats what i used `.+{(.+)}` – Avinash Raj Nov 28 '14 at 12:46
I think you should remove all the look-behind entries in your answer to prevent confusion. – nhahtdh Nov 28 '14 at 12:47

score -1 · Answer 2 · answered Nov 28 '14 at 12:10

-1

Uses an anchor to specify the pattern should match when at the end of a line.

(?<=[{]).*(?=[}]$)

answered Nov 28 '14 at 12:10

SierraOscar

2 Answers2