实际工作中，可能会遇到c++的一些高级特性，例如std::invoke，此函数是c++17才引入的，如何判断当前的gcc是否支持c++17呢，这里提供两种办法。
1.根据gcc的版本号来推断
gcc --version，可以查看版本号，笔者的电脑，gcc的版本号是8.3.0，然后查看8.3.0是什么时候发布的，查出是2019年发布的，从而推断出是支持，但是不是十分肯定，所以接着看第二种方法
2.直接man gcc
上图中，红色方框-std=表示支持的标准项，可以看到c11,c17之类的
centos 本身自带的版本是不支持到C17的。截取 man gcc如下
-std= Determine the language standard. This option is currently only supported when compiling C or C++. The compiler can accept several base standards, such as c90 or c++98, and GNU dialects of those standards, such as gnu90 or gnu++98. When a base standard is specified, the compiler accepts all programs following that standard plus those using GNU extensions that do not contradict it. For example, -std=c90 turns off certain features of GCC that are incompatible with ISO C90, such as the "asm" and "typeof" keywords, but not other GNU extensions that do not have a meaning in ISO C90, such as omitting the middle term of a "?:" expression. On the other hand, when a GNU dialect of a standard is specified, all features supported by the compiler are enabled, even when those features change the meaning of the base standard. As a result, some strict-conforming programs may be rejected. The particular standard is used by -Wpedantic to identify which features are GNU extensions given that version of the standard. For example -std=gnu90 -Wpedantic warns about C++ style // comments, while -std=gnu99 -Wpedantic does not. A value for this option must be provided; possible values are c90 c89 iso9899:1990 Support all ISO C90 programs (certain GNU extensions that conflict with ISO C90 are disabled). Same as -ansi for C code. iso9899:199409 ISO C90 as modified in amendment 1. c99 c9x iso9899:1999 iso9899:199x ISO C99. Note that this standard is not yet fully supported; see <http://gcc.gnu.org/c99status.html> for more information. The names c9x and iso9899:199x are deprecated. c11 c1x iso9899:2011 ISO C11, the 2011 revision of the ISO C standard. Support is incomplete and experimental. The name c1x is deprecated. gnu90 gnu89 GNU dialect of ISO C90 (including some C99 features). This is the default for C code. gnu99 gnu9x GNU dialect of ISO C99. When ISO C99 is fully implemented in GCC, this will become the default. The name gnu9x is deprecated. gnu11 gnu1x GNU dialect of ISO C11. Support is incomplete and experimental. The name gnu1x is deprecated. c++98 c++03 The 1998 ISO C++ standard plus the 2003 technical corrigendum and some additional defect reports. Same as -ansi for C++ code. gnu++98 gnu++03 GNU dialect of -std=c++98. This is the default for C++ code. c++11 c++0x The 2011 ISO C++ standard plus amendments. Support for C++11 is still experimental, and may change in incompatible ways in future releases. The name c++0x is deprecated. gnu++11 gnu++0x GNU dialect of -std=c++11. Support for C++11 is still experimental, and may change in incompatible ways in future releases. The name gnu++0x is deprecated. c++1y The next revision of the ISO C++ standard, tentatively planned for 2017. Support is highly experimental, and will almost certainly change in incompatible ways in future releases. gnu++1y GNU dialect of -std=c++1y. Support is highly experimental, and will almost certainly change in incompatible ways in future releases.
