GetExtension is a file I/O std::string code snippet to get a filename's extension.
Thanks goes to Curtis Krauskopf, who supported me to improve the (terrible and error-prone) STL version GetExtension.
Operating system(s) or programming environment(s)
Lubuntu 15.04 (vivid)
Qt Creator 3.1.1
- G++ 4.9.2
Libraries used:
STL: GNU ISO C++ Library, version
4.9.2
Qt project file: ./CppGetExtension/CppGetExtension.pro
include(../../ConsoleApplication.pri) #Or use the code below # QT += core # QT += gui # greaterThan(QT_MAJOR_VERSION, 4): QT += widgets # CONFIG += console # CONFIG -= app_bundle # TEMPLATE = app # CONFIG(release, debug|release) { # DEFINES += NDEBUG NTRACE_BILDERBIKKEL # } # QMAKE_CXXFLAGS += -std=c++11 -Wall -Wextra -Weffc++ # unix { # QMAKE_CXXFLAGS += -Werror # } include(../../Libraries/BoostAll.pri) SOURCES += main.cpp
#include <cassert> #include <string> #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Weffc++" #pragma GCC diagnostic ignored "-Wunused-local-typedefs" #include <boost/filesystem.hpp> #include <boost/xpressive/xpressive.hpp> #pragma GCC diagnostic pop //Returns the extension of a filename //Assumes that the filename has an extension //From http://www.richelbilderbeek.nl/CppGetExtension.htm const std::string GetExtensionStl(const std::string& filename) { const std::size_t i = filename.rfind('.'); assert(i != std::string::npos && "Filename must contain a dot"); assert(i != filename.size() - 1 && "Filename must not end with a dot"); assert(filename[i+1] != '\\' && "Filename must have an extension"); assert(filename[i+1] != '/' && "Filename must have an extension"); return filename.substr(i,filename.size()); } //Returns the extension of a filename //From http://www.richelbilderbeek.nl/CppGetExtension.htm const std::string GetExtensionBoostFilesystem(const std::string& filename) { return boost::filesystem::extension(filename); } //Returns the extension of a filename //From http://www.richelbilderbeek.nl/CppGetExtension.htm const std::string GetExtensionBoostXpressive(const std::string& filename) { const boost::xpressive::sregex rex = boost::xpressive::sregex::compile( "(.*)?(\\.[A-Za-z]*)" ); boost::xpressive::smatch what; if( boost::xpressive::regex_match( filename, what, rex ) ) { return what[2]; } return ""; } #include <iostream> int main() { assert(GetExtensionStl("test.abc") == ".abc"); assert(GetExtensionStl("myfolder/test.abc") == ".abc"); assert(GetExtensionStl("myfolder\\test.abc") == ".abc"); assert(GetExtensionStl("myfolder/myfolder/test.abc") == ".abc"); assert(GetExtensionStl("myfolder\\myfolder\\test.abc") == ".abc"); assert(GetExtensionBoostFilesystem("test.abc") == ".abc"); assert(GetExtensionBoostFilesystem("myfolder/test.abc") == ".abc"); assert(GetExtensionBoostFilesystem("myfolder\\test.abc") == ".abc"); assert(GetExtensionBoostFilesystem("myfolder/myfolder/test.abc") == ".abc"); assert(GetExtensionBoostFilesystem("myfolder\\myfolder\\test.abc") == ".abc"); assert(GetExtensionBoostXpressive("test.abc") == ".abc"); assert(GetExtensionBoostXpressive("myfolder/test.abc") == ".abc"); assert(GetExtensionBoostXpressive("myfolder\\test.abc") == ".abc"); assert(GetExtensionBoostXpressive("myfolder/myfolder/test.abc") == ".abc"); assert(GetExtensionBoostXpressive("myfolder\\myfolder\\test.abc") == ".abc"); for (auto f: { GetExtensionStl, GetExtensionBoostFilesystem, GetExtensionBoostXpressive} ) { assert(f("test.abc") == ".abc"); assert(f("myfolder/test.abc") == ".abc"); assert(f("myfolder\\test.abc") == ".abc"); assert(f("myfolder/myfolder/test.abc") == ".abc"); assert(f("myfolder\\myfolder\\test.abc") == ".abc"); } }