C++11 的支持

C++11标准在2011年8月份获得一致通过，这是自1998年后C++语言第一次大修订，对C++语言进行了改进和扩充。随后各编译器厂商都各自实现或部分实现了C++中的特性。

目前来看GCC是对C++11支持程度最高最多的编译器，必须升级GCC至4.8版以上以支持C++11。

查看你的gcc版本

zeno@vm-zinc:~$ gcc  -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.8/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.8.2-19ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs --enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.8 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-libmudflap --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) 

写段代码测试下

#include 
#include 
#include 
#include 
#include 
  
int main()
{
    // construction uses aggregate initialization
    std::array a1{ {1,2,3} };  // double-braces required
    std::array a2 = {1, 2, 3}; // except after =
    std::array a3 = { {std::string("a"), "b"} };
  
    // container operations are supported
    std::sort(a1.begin(), a1.end());
    std::reverse_copy(a2.begin(), a2.end(), 
                      std::ostream_iterator(std::cout, " "));
  
    std::cout << 'n';
  
    // ranged for loop is supported
    for(auto& s: a3)
        std::cout << s << ' ';
    std::cout << 'n';    
}

编译并且运行

g++ -std=c++11 -o stdarray stdarray.cpp #一定要加上c++11，否则可能无法编译或者无法运行。

运行：./stdarray;

结果输出：3 2 1 na b 则证明成功了

如果在QT中要开启C++11的支持，需要在项目的pro文件中开启

QMAKE_CXXFLAGS = -fpermissive  -std=c++11

下面玩一段正则表达式试试

// regex_match example
#include 
#include 
#include 

int main ()
{

  if (std::regex_match ("subject", std::regex("(sub)(.*)") ))
    std::cout << "string literal matched\n";

  const char cstr[] = "subject";
  std::string s ("subject");
  std::regex e ("(sub)(.*)");

  if (std::regex_match (s,e))
    std::cout << "string object matched\n";

  if ( std::regex_match ( s.begin(), s.end(), e ) )
    std::cout << "range matched\n";

  std::cmatch cm;    // same as std::match_results cm;
  std::regex_match (cstr,cm,e);
  std::cout << "string literal with " << cm.size() << " matches\n";

  std::smatch sm;    // same as std::match_results sm;
  std::regex_match (s,sm,e);
  std::cout << "string object with " << sm.size() << " matches\n";

  std::regex_match ( s.cbegin(), s.cend(), sm, e);
  std::cout << "range with " << sm.size() << " matches\n";

  // using explicit flags:
  std::regex_match ( cstr, cm, e, std::regex_constants::match_default );

  std::cout << "the matches were: ";
  for (unsigned i=0; i
运行结果：
// regex_match example
#include 
#include 
#include 

int main ()
{

  if (std::regex_match ("subject", std::regex("(sub)(.*)") ))
    std::cout << "string literal matched\n";

  const char cstr[] = "subject";
  std::string s ("subject");
  std::regex e ("(sub)(.*)");

  if (std::regex_match (s,e))
    std::cout << "string object matched\n";

  if ( std::regex_match ( s.begin(), s.end(), e ) )
    std::cout << "range matched\n";

  std::cmatch cm;    // same as std::match_results cm;
  std::regex_match (cstr,cm,e);
  std::cout << "string literal with " << cm.size() << " matches\n";

  std::smatch sm;    // same as std::match_results sm;
  std::regex_match (s,sm,e);
  std::cout << "string object with " << sm.size() << " matches\n";

  std::regex_match ( s.cbegin(), s.cend(), sm, e);
  std::cout << "range with " << sm.size() << " matches\n";

  // using explicit flags:
  std::regex_match ( cstr, cm, e, std::regex_constants::match_default );

  std::cout << "the matches were: ";
  for (unsigned i=0; i