Preprocessor "#" 用法
Formal parameters are not replaced within quoted strings. If, however, a parameter name is preceded by a # in the replacement text, the combination will be expanded into a quoted string with the parameter replaced by the actual argument. This can be combined with string concatenation to make, for example, a debugging print macro: #define dprint(expr) printf(#expr " = %gn", expr) When this is invoked, as in dprint(x/y) the macro is expanded into printf("x/y" " = &gn", x/y); and the…