What c_str() really returns

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I have a confusion with the member function string::c_str().
Does it create a new char array, copies the contents then returns the pointer of the initial element ? or just a pointer to the already created array ?
But if so, why a code like the one below won't destroy the string object?

C++

string s = "Hi Sam";
const char *c = s.c_str();
delete c;

Thanks, Sam.

Posted 12-Dec-15 6:26am

Samuel Shokry

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Philippe Mori 12-Dec-15 23:05pm

There are tools and compiler options to help find such problems but it is better to never write undefined code to start with and a good way to do so is to avoid explicit memory allocation and desallocation as it is error prone.

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KarstenK · Answer 1 · 2015-12-12T07:36:00

Solution 1

This is really a question you should solver yourself bei googling for the answer.

Explained means it, that it returns the pointer to the inner string of the object. So it is NOT a new object or memory block.

Use the detail view of your debugger to see the inner guts of objects.

Posted 12-Dec-15 7:36am

KarstenK

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Samuel Shokry 12-Dec-15 13:40pm

First of all thanks for your reply.
I have googled it, and I understood that it is a pointer to the inner data, but what about calling delete, why doesn't it cause any problem to the string object ?

Aescleal · Answer 2 · 2015-12-12T09:32:00

The code you presented could do just about anything in a C++ program - its behaviour is undefined.

So what makes it undefined? Two things in this case:

- you're deleting something that hasn't been allocated by new
- You're deleting an array using the wrong form of delete

So unless the contract for a class tells you to delete something, DON'T!