Char / string Question

**cboard_member** · 07-11-2005

Now I like the way C++ handles strings; I find parsing so much easier in every way.

But...

Here's the way I handle strings and such, a few code examples. I was just wondering if there's a more efficient way, or if I'm doing some n00b error type things.

Code:

#include <iostream>
using namespace std;

int main ()
{
        char* buffer = new char[120];
        
        cout << "Enter a sentance: ";
        cin >> buffer;

        delete [] buffer;
        return 0;
}

A pretty useless example i know, but anyway...

Code:

#include <iostream>
using namespace std;

char* ret_buffer ()
{
        char* buf = new char[50];
        return buf;
}

int main ()
{
        char* buffer = new char[50];

        strcpy (buffer, ret_buffer(), 50);
        delete [] buffer;
        return 0;
}

And another.

I was just wondering if there are any glaring mistakes? I just feel like I'm doing something wrong but can't put my finger on it. I have quarms about my second example where the function 'ret_buffer()' returns the pointer to a buffer (buf) which is never delete []'d.

Any help appreciated

.

PS Please don't point out syntax errors I'll notice them after i've posted this and won't really care - we all know what it's supposed to do.

**dwks** · 07-11-2005

The second one is returning a local variable . . . not good.

**~~ILoveVectors~~** · 07-11-2005

Code:

#include <iostream>
#include <string>

using namespace std;

int main()
{
     string S1 = "my name is";
     cout << S1;
     S1 += " Petey Pablo!";
     cout << S1 << endl;
     cin.get();
     return 0;
}

Code:

#include <iostream>
#include <string>

using namespace std;

int main()
{
     string userinput;
     cout << "Enter a string!  : ";
     getline(cin, userinput, '\n');
     cout << userinput;
     cin.get();
     return 0;
}

**Daved** · 07-11-2005

Your qualms about the second example are correct. The memory you allocate in ret_buffer is never cleaned up, and you have a memory leak.

BTW, that is how C handles strings. C++ handles strings with a string class that handles all the memory management for you so you don't have to worry about these things. Look up the C++ string class in the <string> standard header as ILoveVector's examples show.

Also, the second one does not return a local variable, that statement is incorrect. It returns a pointer to dynamic memory, but that pointer is not saved and the memory is leaked.

**cboard_member** · 07-11-2005

I knew I was doing something wrong. I spelt qualms 'quarms'. Tutt. Summer heat.

Thanks to all for your help!

**^xor** · 07-11-2005

Originally Posted by dwks

The second one is returning a local variable . . . not good.

I don't see any problem with that as long as you remember to save the return value to a new pointer. The allocated memory from new is not local.

**cboard_member** · 07-11-2005

Duly noted. Cheers.

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