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C's predefined macros

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

On Sunday, March 21st 2004 at 10:43 AM
By Andrew Pociu (View Profile)
****-   (Rated 3.3 with 10 votes)
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__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
}
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Rate Rate this tutorial
Comment Current Comments
by Platone on Thursday, October 14th 2004 at 11:10 AM

It is not the current system time / date, but the BUILDING time / date!!!
It works, but it's not what is printed!
Bye

by antred on Tuesday, February 14th 2006 at 11:03 AM

Of course it is, and I doubt the author was implying anything else.

by nazareth on Tuesday, October 10th 2006 at 06:09 PM

want to know about C will be great if ull forward me some Literature on it thanking u see u


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