813193_0_0_26890.c 813193_0_0_26890.c(4) : error C2065: “inta” : 未声明的标识符 813193_0_0_26890.c(4) : error C2065: “b” : 未声明的标识符 813193_0_0_26890.c(4) : error C2065: “sum” : 未声明的标识符 813193_0_0_26890.c(5) : error C2065: “a” : 未声明的标识符