Re: char array and delete

Carl Barron <>
Thu, 27 Mar 2008 07:07:06 CST
In article
<> wrote:

when i do
char * text = "foo";
and later in a if condition i can assign it to another one that was
allocated with new
how do i know if i can call delete[] on text ?
if i delete[] text when text was assigned as char * text = "foo"; i
get an error.

    with just char * text, you can't.

    with some class it is possible. My choice would be shared_ptr<char>
with one of two deleters but that is only because I don't know more
about how text is used.
    struct no_deleter
       void operator (void *){}

    struct array_deleter
       void operator ()( char *p) {delete [] p;}

    inline char * create_on_stack(char *p)
       return shared_ptr<char>(p,no_deleter());

    inline char * create_on_heap(int n)
       return shared_ptr<char>(new char[n],array_deleter());

    and use the appropriate of the free functions above to get a
shared_ptr<char>. then

    shared_ptr<char> text = create_on_stack("Hello World");
    // ...
    text = create_on_heap(100);
    would delete [] text when appropriate.

    There would be no operator [] for text, but anytime you want to
manipulate the text string text.get() would return a char * just don't
delete it and so if text is a local variable of main()

void do_something(shared_ptr<char> &p)
       p = create_on_heap(1000);
int main()
    shared_ptr<char> text = create_on_stack("Hello World")

would delete [] or not delete at all depending on whether the ptr was
move to the heap or not.

This is not the only solution, but probably easiest to use...

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