Simple Regex Usage in C++

Question

I try to do the most basic regex example in C++ using the default lib, and I keep getting either crashes or incoherent behavior.

// with -std=c++11
#include <regex>
using namespace std;

int main()
{
    // Copied from the documentation, this one works
    if (std::regex_match ("subject", std::regex("(sub)(.*)") ))
        std::cout << "string matched\n";
    // The most simple example I could try, crash with "regex_error"
    if (std::regex_match ("99", std::regex("[0-9]*") ))
        std::cout << "integer matched\n";
}

I've tried multiple syntaxes and flags, but nothing seems to work. Since my code seems to be matching all the examples I can find, I'm struggling to see what I'm missing.

@Dillinur gcc is up to 6.1 now. You could try upgrading your compiler. — erip
– erip, Commented May 16, 2016 at 10:46
@Dillinur: At least do not use regex patterns that match empty strings. Why do you need an empty (null) string? Just use [0-9]+. — Wiktor Stribiżew
– Wiktor Stribiżew, Commented May 16, 2016 at 10:49
I was just trying all the possible regex, any of the '*' '+' chars were just crashing the regex constructor.. — Dillinur
– Dillinur, Commented May 16, 2016 at 11:21

Dillinur · Accepted Answer · 2016-05-16 11:20:32Z

1

As @Wiktor Stribiżew stated, it was just my compiler being too old. Updating the compiler (from gcc 4.1 to gcc 4.9) solved the problem!

answered May 16, 2016 at 11:20

Dillinur

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