An empty base struct that defines types that may be inherited by derived classes that provides a binary function object. Deprecated in C++11, removed in C++17.
binary_function
结构在C++11标准中已废弃,在C++17标准中已移除该结构,所以使用该结构的最高可使用C++标准为C++14.
要使用该要工程的配置中最高只能选择C++14
如果选择了C++17或者C++20会报下面错误: