1009865_0_0_30304.cpp 1009865_0_0_30304.cpp(5) : error C2065: “cin” : 未声明的标识符 1009865_0_0_30304.cpp(6) : error C2065: “cout” : 未声明的标识符 1009865_0_0_30304.cpp(6) : error C2065: “endl” : 未声明的标识符