465079_0_0_30345.cpp 465079_0_0_30345.cpp(8) : error C2065: “cin” : 未声明的标识符 465079_0_0_30345.cpp(12) : error C2065: “cout” : 未声明的标识符 465079_0_0_30345.cpp(12) : error C2065: “endl” : 未声明的标识符