0_0_38916826_2855.cpp 0_0_38916826_2855.cpp(10) : error C2065: “sum1”: 未声明的标识符 0_0_38916826_2855.cpp(20) : error C2065: “sum1”: 未声明的标识符 0_0_38916826_2855.cpp(21) : error C2065: “sum1”: 未声明的标识符