c++ - Gettin line number of the called function

Question

Please let me know if I can do it or not?

I am writing a library that could work to track memory allocation and de-allocation in C++. In short, I am trying to see if my application does not have any memory leaks. This is what I did so far.

Overrode the new and the delete operator and now. Whenever the application uses new, I am planning to store the address and the number of bytes that are allocated in that call. Similarly, when the delete is called on that address, I will remove that from the stored list. Until now its fine. But I want to store the file name and the line number from where the "new" is called. I can do that only in the overridden new. Is there a way to get line number in the overridden function?

---

1    int main()
2    {
3       // Say, A is a structure
4        A *a = new A();
5        return 0;
6     }
7    void* operator new( size )
8    {
9        //
10       // store the line number and file name on line 4 ??? Can I do it?
11       return (malloc(size));
12   }
------------------------

Answer 1

Since C++20 you can use std::source_location which offers:

• line
• column
• file_name
• function_name

For previous versions of C++, traditionnally the macros __LINE__ gives the line number but also __FUNCTION__ and __FILE__ are really helpful, giving the const char* of the enclosing function, and file name.

Indeedn, __FUNCTION__ is not standard but supported by several compilers.

Unfortunately these macros only take their value in place. So it is not possible for you to ask for the caller.

You should write the __LINE__ and __FILE__ macros everywhere you use new. :(.