C language macro

The ansi c standard has several predefined macros: __file _ date _ time ___ _ line _.

_ Line __: inSource codeInsert Current SourceCodeRow number;

_ File __: insert the name of the current source file into the source file;

_ Date __: Insert the current compilation date into the source file

_ Time __: Insert the current compilation time into the source file;

_ Stdc __: when requiredProgramWhen the ansi c standard is strictly followed, this identifier is assigned a value of 1;

_ Cplusplus: This identifier is defined when a C ++ program is compiled.

These macros are useful ~~~~~~~~

When debugging a program or compiling a program, __line _ is useful. It can be used to print the line numbers of logical errors ~~~~~~~, Example:

Switch (X)

{

Case 1:

....;

Break;

 

Case 2:

.....;

Break;

 

Default:

Printf ("logic erro line number % d! /N ",__ line __);

Break;

}

Another example is to use _ date _ and _ time _ to insert the Compilation Time.

Code:

Void print_version_info (void)

{

Printf ("date compiled: % s/n" ,__ date __);

Printf ("timecompiled: % s/n" ,__ time __);

}

Output Format: Mm dd yy and HH: mm: SS

In this way, you can implement version control and know when you have compiled it ~~