Do C++11 regular expressions work with UTF-8 strings?

Question

If I want to use C++11's regular expressions with unicode strings, will they work with char* as UTF-8 or do I have to convert them to a wchar_t* string?

Answer 1

You would need to test your compiler and the system you are using, but in theory, it will be supported if your system has a UTF-8 locale. The following test returned true for me on Clang/OS X.

bool test_unicode() {     std::locale old;     std::locale::global(std::locale("en_US.UTF-8"));      std::regex pattern("[[:alpha:]]+", std::regex_constants::extended);     bool result = std::regex_match(std::string("abcdéfg"), pattern);      std::locale::global(old);      return result; } 

NOTE: This was compiled in a file what was UTF-8 encoded.

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Just to be safe I also used a string with the explicit hex versions. It worked also.

bool test_unicode2() {     std::locale old;     std::locale::global(std::locale("en_US.UTF-8"));      std::regex pattern("[[:alpha:]]+", std::regex_constants::extended);     bool result = std::regex_match(std::string("abcd\xC3\xA9""fg"), pattern);      std::locale::global(old);      return result; } 

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Update test_unicode() still works for me

$ file regex-test.cpp  regex-test.cpp: UTF-8 Unicode c program text  $ g++ --version Configured with: --prefix=/Applications/Xcode-8.2.1.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1 Apple LLVM version 8.0.0 (clang-800.0.42.1) Target: x86_64-apple-darwin15.6.0 Thread model: posix InstalledDir: /Applications/Xcode-8.2.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin