Segmentation fault c++ regex

Question

I am getting a "Segmentation fault" when I try to use some regular expressions. In this example, the first regular expression worked fine, but the second produced a segmentation fault:

#include <regex>
#include <iostream>

using namespace std;

void out(const string& s, const string& d,bool b) { cout << s << ", " << d << (b ? "=found" : "=not found") << endl; }

int
main()
{
    const auto exp1 = string{"<.*>.*</.*>"};
    const auto reg1 = regex{exp1};
    const auto data1 = string{"<tag>value</tag>"};
    const auto found1 = regex_match(data1, reg1);
    out(exp1, data1, found1);

    const auto exp2 = string{"<(.*)>.*</\\1>"};

    cout << "About to create the regex!" << endl;
    const auto reg2 = regex{exp2};
    cout << "done." << endl;

    const auto data2 = string{"<tag>value</tag>"};
    const auto found2 = regex_match(data2, reg2);
    out(exp2, data2, found2);

    cout << "All done!" << endl;
}

I compile it like this:

g++ -O0 -g -Wall -Wpedantic -std=c++11    try3.cpp   -o try3

And when I run it I get this:

$ ./try3
<.*>.*</.*>, <tag>value</tag>=found
About to create the regex!
Segmentation fault

I am running on CentOS release 5.11 with libstdc++-4.1.2-55.el5

That is a problem with the compiled regex library, not the regex itself. You can tell if it's this if you put a try/catch around that line, but it is never caught. — , Feb 10 '17 at 18:19
@sln: true, I tried earlier with a try statement and it does not catch anything. Do you (or others) have a work-around? — Scott Nelson, Feb 10 '17 at 19:21
Not for sure, but google the problem, it's probably either the lib version or what flags were set when compiled. Somebody should pass by that knows for sure. — , Feb 10 '17 at 19:25
Do you also have the same issue with `<[^>]*>[^<]*[^>]*>` or `"<([^<]+)>[\\s\\S]*?\\1>"`? If yes, the problem is with the outdated regex library. — Wiktor Stribiżew, Feb 10 '17 at 20:32

score 1 · Accepted Answer · edited May 23 '17 at 11:54

1

This is because GCC 4.1 was starting to implement regex but it was not ready for use until later.

See Is gcc 4.8 or earlier buggy about regular expressions?

edited May 23 '17 at 11:54

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answered May 18 '17 at 14:08

Scott Nelson

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Segmentation fault c++ regex

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