C + + Primer Learning notes (i)

1. Function of the condition indicator

#define Book_h/    *  Book.h content prevents duplicate processing of header files */#endif  

When compiling a C + + program, the compiler automatically defines a preprocessor's name __cplusplus, so it can be used to determine if the program is a C + + program

#ifdef __cplusplus     extern " C " #endif    int min (intint);

Two more useful predefined names are: __line__ and __file__. __line__ the number of rows that the record file has been compiled, __file__ contains the name of the file being compiled.

if 0 )    "Error:" << __file__           "" << __line__           "element_count must be non-zero.\n";

2.

C + + Primer Learning notes (i)