__LINE__ macros in the C language

In the C language, there are four predefined macros:

Current file: __file__

Current line number: __line__

Current Date: __date__

Current time: __time__

These 4 macros are replaced by the compiler with actual values or strings when the code is compiled.

Here is a snippet of code that compiles a code: TEST.C

1 #include <stdio.h>2void  main ()3{4     printf ("  %s \ n%d \n%s \ n%s \ n", __file__,__line__,__date__,__time__); 5 }

The result of his operation is:

test.c   4  about     £ º

Only the line number is an integer, the other 3 is a string , it is very convenient to use it!

__file__,__line__ is useful when debugging a program ;

__date__,__time__ is useful when confirming the program compile time (version reference ).

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__LINE__ macros in the C language