Re: Cannot use DEBUG_NEW to trace this leak.

"Giovanni Dicanio" <>
Wed, 23 Jan 2008 20:51:40 +0100
"Simon" <> ha scritto nel messaggio

I have narrowed down the code as follow where the error could be.
I would rather not change the code as much as possible.

// in the constructor
m_pData = new std::string[ someKnownSize + 1]

What are you doing here?
Are you allocating a raw vector (new[]) of std::string's?
The above code seems erroneous to me.

If you want to allocate a vector (list) of strings, I would suggest
std::vector, i.e.:

#include <vector>
#include <string>

 typedef std::vector< std::string > StringList;

 StringList myStrings( howManyStrings );

Or do you want to allocate a *single* string?
In this case, just a std::string instantiation is fine.

memset( m_pData, 0, (n+1)*sizeof(std::string) );

Please use memset() only for POD (plain old data).
And sizeof(std::string) is not very meaningful in this context...

// The destructor
if( NULL != m_pData )
   delete [] ( m_pData );
m_pData = NULL;
m_nSize = 0;

If you use std::vector< std::string >, you don't need to do anything in the
destructor; std::vector and std::string destructors properly take care of
their own resource cleanup.

// in a function
void add( std::string &s, int len )
   m_pData[m_nSize++] = std::string(s, len ) ;


if I remove the lines m_pData[m_nSize++] = std::string(s, len ) ; then
I have no leak.

I would use std::vector< std::string > to store the list of strings.
It's very easy:

  std::vector< std::string > myStrings;
  myStrings.push_back( std::string( "Bob" ) );
  myStrings.push_back( std::string( "Jeff" ) );

  ... etc.

And if you want to access the i-th string in the list, you can use:

 myStrings[i] // no bounds checking on index 'i' // more safe, does bounds checking on 'i'


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