Equivalent of __LINE__ macro relative to beginning of function

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In C/C++, is there a macro that would tell me a line number relative to the beginning of the function in which the macro is found, rather than relative to the beginning of the file?

c-preprocessor c
1 Answers

No, but you can do something somewhat equivalent by creating a line offset:

int func(char *s)
{   static const int begin_line = __LINE__;
    #define func_line (__LINE__ - begin_line)
    /* ... */
    printf("%s():%d\n", __func__, func_line);
}

Output:

func():3

Note that begin_line being placed on the same line as the bracket is important. If you want zero-based line indexes then feel free to add a newline.

In C++ you can use constexpr instead of static const for compile-time evaluation of begin_line.

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