Cross-platform development and serialization (predefined macros under the c99 Standard)

Some predefined macros are specified in the C standard and are often used in programming. The following table lists some predefined macros that are frequently used.

 

_ Date _ Date of preprocessing (string text in the form of "Mmm dd YYYY)

_ File _ represents the string Text of the current source code file name

_ Line _ represents the integer constant of the row number in the current source code.

_ Time _ source file Compilation Time in the format of "HH: mm: SS"

_ FUNC _ the current function name // added to c99, which is not supported by some Compilers

 

It is useful for macros such as _ file __,__ line __,__ func _ in program debugging, because you can easily know the row of the file to which the program runs and the function.

The following example prints the predefined macros.

 

# Include <stdio. h>

# Include <stdlib. h>

Void why_me ();

Int main ()

{

Printf ("the file is % S.", _ file __);

Printf ("the date is % S.", _ date __);

Printf ("the time is % S.", _ time __);

Printf ("this is line % d.", _ line __);

Printf ("this function is % S.", _ FUNC __);

Why_me ();

Return 0;

}

 

Void why_me ()

{

Printf ("this function is % s", _ FUNC __);

Printf ("the file is % S.", _ file __);

Printf ("this is line % d.", _ line __);

}