main.cpp|64|error: 'cout' was not declared in this scope|

文件中已引入：#include <iostream>
原因是未指定：using namespace std;
C++ 1998要求 cout and endl 使用std::cout,std::endl格式，或者在程序开始申明“ using namespace std;”,不然会出现”cout was not declare this in scope“的错误