Re: memory leak in the code?

kwikius wrote:


...


Excellent :). As i know, for each program we get at least one (hard to
detect and with random runtime apperance) error due to improper delete/
delete[] usage.

For example, the stupid program ( http://grizlyk1.narod.ru/cpp_new/gcc/utils=

) for adding source lines into gcc asm output has 3 levels of patching
of detected errors. Take a look at the last patch, file "to_do.txt":

1. possible memory leakage.

    void Terr::do_copy(const char *const who)
     {
      if(who)try
       {
        const uint len=strlen(who);
        if(!len)return;

        char *const tmp=new char[len+1];
        strcpy(tmp,who);
        msg_copied=tmp;
       }
      catch(...){ msg_shared="no memory"; }
     }

"strcpy(tmp,who)" can throw while "tmp" has no owner

patch:
        char *const tmp=new char[len+1];
        try{ strcpy(tmp,who); }catch(...){ delete[] tmp; throw; }
        msg_copied=tmp;

2. Wrong delete for arrray

    ~Terr::Terr(){ delete msg_copied; }

patch:
    ~Terr::Terr(){ delete[] msg_copied; }

3. Wrong delete for arrray

    Terr& operator= (const Terr& obj)
     {
      if( &obj != this )
       {
        msg_shared=obj.msg_shared;
        delete msg_copied; msg_copied=0;
        do_copy(obj.msg_copied);
       }
      return *this;
     }

patch:
        if(msg_copied){delete[] msg_copied; msg_copied=0;}

I agree, that the errors appeared due to my negligent work, this is
very bad habbit for programming, but there are many other people with
the same behaviour in the world. This is constant fact of nature :).

And in addition, any desing work, being continuous iterational
process, inspires a little the negligence in work ( :) I have found
the couse ).

So, the only way to prevent the errors is explicit memory
declarations:

char * ptr; //C-style pointer
auto char * ptr; //can not delete/delete[]
heap char * ptr; //can delete heap/delete
heap[] char * msg_copied; //can delete heap[]/delete[]
other_memory_type char *ptr; //can delete other_memory_type

Maybe it will be added to C++.

Maksim A. Polyanin
old page about some C++ improvements:
http://grizlyk1.narod.ru/cpp_new