No matches with c++11 regex [duplicate]

Answer 1

According to this change log <regex> is supported in gcc-4.9 with libstd++-v3

http://gcc.gnu.org/gcc-4.9/changes.html

Answer 2

Because <regex> is not yet implemented in libstdc++, as documented here (§28).

For now, use Boost.Xpressive or Boost.Regex instead.

Answer 3

By now your example runs correctly:

$ ~/src/gcc/inst/bin/g++ --version
g++ (GCC) 4.9.0 20140224 (experimental)

on

$ uname -a
Linux ... x86_64 x86_64 x86_64 GNU/Linux

executes

$ ./83-regex.x 
true
1