Standard C pre-defined symbols

__FILE__ a string that holds the path/name of the compiled file
__LINE__ an integer that holds the number of the current line number
__DATE__ a string(Mmm dd yyyy) that holds the current system date
__TIME__ a string(hh:mm:ss) that holds the current system time
__STDC__ defined as the value '1' if the compiler conforms with the ANSI C standard
__cplusplus determines if your compiler is in C or C++ mode. Usually used in headers


#include <stdio.h>


void main(void)
{
    printf("The path/name of this file is %s\n", __FILE__);
    printf("The current line is %d\n", __LINE__);
    printf("The current system date is %s\n", __DATE__);
    printf("The current system time is %s\n", __TIME__);


    #ifdef __STDC__
    printf("The compiler conforms with the ANSI C standard\n");
    #else
    printf("The compiler doesn't conform with the ANSI C standard\n");
    #endif


    #ifdef __cplusplus
    printf("The compiler is working with C++\n");
    #else
    printf("The compiler is working with C\n");
    #endif
}