Dynamically allocate array of std::string

Question

I want to dynamically allocate an array of std::string. There is a function to allocate. I can call the function as many number of times as I want through out the program. If the pointer to the array is already allocated, I want to release the memory first then allocated the new one.

Here is what I tried:

std::string *names;
bool already_allocated = false;
void allocate( int n)
{
    if( already_allocated)
    {
        delete names;
    }
    names = new std::string[n];
    already_allocated = true;
}

int main()
{
    allocate(5);
    allocate(6);
    return 0;
}

But it is giving runtime error in the 2nd allocate() call for the line delete names

Am I misunderstanding something?

Why not use std::vector<std::string> and resize?

Andrei
– Andrei

2013-06-01 11:27:07 +00:00
Commented Jun 1, 2013 at 11:27 — Andrei
– Andrei, Commented Jun 1, 2013 at 11:27

Marc Claesen · Accepted Answer · 2013-06-01 11:19:18Z

2

You have to use delete [] names; because you want to delete an array of strings, delete names; deletes a single object.

answered Jun 1, 2013 at 11:19

Marc Claesen

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HepaKKes · Accepted Answer · 2013-06-01 11:21:53Z

2

You cannot invoke delete names on an array, you should use

 delete[] names

instead.

How about use a std::vector<std::string> for your names data sructure instead?

answered Jun 1, 2013 at 11:21

HepaKKes

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Comments

Daemon · Accepted Answer · 2013-06-01 11:24:22Z

1

When you allocate memory using new you can use delete operator but when you allocate memory using new[] then to avoid memory leak use delete[] operator, to delete memory allocated for an array.

delete[] names

answered Jun 1, 2013 at 11:24

Daemon

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