A list of C's predefined macros (__FILE__, __LINE__, __STDC__...) with description and an example of how to use them.

__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 that holds the current system date;
__TIME__ – a string 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
}