0_0_39636813_18137.cpp 0_0_39636813_18137.cpp(5) : error C2065: “i”: 未声明的标识符 0_0_39636813_18137.cpp(6) : error C2065: “sum”: 未声明的标识符 0_0_39636813_18137.cpp(6) : error C2065: “i”: 未声明的标识符