Print name of caller function

Question

I found __FUNCTION__ macro that will give the name of currently executing function, But is there any macro available to print the name of parent function (a function that invoked currently running function) ?

void print_error_message(const char *msg)
{
    printf("%s : %s\n",__FUNCTION__,msg);
}

int main()
{
    print_error_message("failed to connect");
    return 0;
}

The above program will give output :

print_error_message : failed to connect

But what I actually required is

main : failed to connect

because main() invoked print_error_message()

I don't want to pass one more argument to function print_error_message() like print_error_message(__FUNCTION__, msg), what I am expecting is a similar macro or function to retrieve the name of the caller function.

you can try with this https://stackoverflow.com/questions/16100090/how-can-we-know-the-caller-functions-name — Jahangir, Nov 26 '19 at 11:20
Note that the standard name is `__func__`, which is a pre-defined identifier (see C11 [§6.4.2.2 Predefined identifiers](http://port70.net/~nsz/c/c11/n1570.html#6.4.2.2)). The names `__FUNCTION__` and `__PRETTY_FUNCTION__` are GCC extensions. See [What are the differences between `__PRETTY_FUNCTION__`, `__FUNCTION__` and `__func__`?](https://stackoverflow.com/questions/4384765/whats-the-difference-between-pretty-function-function-func) — Jonathan Leffler, Nov 26 '19 at 11:49
Additionally, the GCC documentation on [function names as strings](https://gcc.gnu.org/onlinedocs/gcc/Function-Names.html) notes: _ These identifiers are variables, not preprocessor macros, and may not be used to initialize char arrays or be concatenated with string literals._ — Jonathan Leffler, Nov 26 '19 at 11:55

Some programmer dude · Accepted Answer · 2019-11-26T11:23:49.770

There's no standard way to get the name from the call-stack, and if debug information is stripped or otherwise unavailable there's possible no way at all to get the name.

As a simple workround, you could use macros:

#define print_error_message(msg) actual_print_error_message(__FUNCTION__, (msg))

void actual_print_error_message(const char *func, const char *msg)
{
    printf("%s : %s\n",func,msg);
}

Note that __FUNCTION__ is not standard C, it's an extension. For standards-compliance use the C99 special predefined variable __func__.

score 2 · Answer 2 · answered Nov 26 '19 at 11:21

You could let the caller pass its function name as a parameter. For example:

void print_error_message(const char *msg, const char *caller)
{
    printf("%s : %s\n",caller,msg);
}

int main()
{
    print_error_message("failed to connect", __FUNCTION__);
    return 0;
}

score 1 · Answer 3 · answered Nov 26 '19 at 11:12

1

No, it is not available and it is not possible.

Because value of a macro like __FUNCTION__ is calculated in preprocessing phase and what you want to do is not possible in that phase.

answered Nov 26 '19 at 11:12

Afshin

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But I hope there may any library functions that can do this job – Ajith C Narayanan Nov 26 '19 at 11:16
Actually, the preprocessor doesn't know what a function is. so `__FUNCTION__` is not handled by the preprocessor. – Jonathan Leffler Nov 26 '19 at 11:50
@JonathanLeffler ? then what phase convert it into function name? – Afshin Nov 26 '19 at 13:29
The compiler proper. It knows what functions are. – Jonathan Leffler Nov 26 '19 at 14:46

alk · Answer 4 · 2019-12-05T09:52:05.367

1

I don't want to pass one more argument to function [...] I am expecting is a similar macro or function to retrieve the name of the caller function.

This does not exist, at least not as part of the C standard.

On Linux GCC provides the capability to pull backtrace info. Perhaps this helps you.

edited Dec 05 '19 at 09:52

answered Nov 26 '19 at 13:03

alk

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Print name of caller function

4 Answers4