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Simple Smart Pointer Implemantation

By , 13 Sep 2006
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Introduction

Sometimes it is necessary to use something automatic instead of classical C++ pointers. For example you want that your pointer is automatically deleted. For this we need a class that automatize this things. Such class is called Smart Pointer.

template<class T><BR>class SmartPointer<BR>{<BR>public:<BR> SmartPointer(T* pointer)<BR>  : mPointer(pointer)<BR> {}<BR> ~SmartPointer()<BR> {<BR>  delete mPointer;<BR>  release();<BR> }<BR> T* get()<BR> {<BR>  return mPointer;<BR> }<BR> void release()<BR> {<BR>  mPointer = NULL;<BR> }<BR> bool valid() const<BR> {<BR>  return mPointer != NULL;<BR> }<BR> T* operator-> ()<BR> {<BR>  return mPointer;<BR> }<BR> T& operator* ()<BR> {<BR>  return *mPointer;<BR> }<BR>private:<BR> T* mPointer;<BR> SmartPointer(SmartPointer&) {}<BR> SmartPointer& operator= (SmartPointer&) {}<BR>};

We need a template class, because it should work with each type. The function get() returns the pointer, with the function valid() you can check whether the pointer has a valid value or not and the function release() sets the value of the pointer to NULL. We overload two operators: -> for the pointer and * for the value of the pointer. The most important thing of the smart pointer is this:

~SmartPointer()
{
  delete mPointer;
  release();
}

In the desctructor we automatically delete the pointer and then we set the value of the pointer to NULL.

This is an example how to use the smart pointer:

int main(int, char**)
{
 SmartPointer<int> pointer(new int); /* create a smart pointer with the type int */
 *pointer = 14; /* set the value to 14 */
 /* ... */
 return 0; 
} /* at the end of the scope the pointer will be automatically deletet */

It is very simple. I hope my article helped you.

License

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About the Author

knoxpointer
Web Developer
Austria Austria
When I was younger I looked on my father when he programmed something. First it was not interesting for me. Later I asked my father to teach me programming. He began to teach me BASIC. Time later I told him it is not so interesting, because that programming language looked very old as that he programmed. 6 months later I programmed some simple applications in Visual Basic. Then there was a month break between me and programming. Then I found more interesting programming language for me, PASCAL. I tried it 3 weeks then I found a book about C#. I began to read it and it was very interesting and something new for me. My father taught me the fundamentals of the programming language and then I programmed some simple console applications, later text editor with syntax coloring. I programmed C# for 3 months. Later I wanted to know how does it work in the background. I started to programme in C++. My father taught me the very basic things in C++, but there were very things that were similar to C# then I borrowed me some books from the library about C++. When I was better in C++, I made some exercises about algorithms and datastructures in C++ with my father. After, I decided me to make my own project. I began to programme at my shell. I used WIN32-API in my project. I like many things in C++, for example that I can programme procedural and object-oriented and lot of other things. I thing C++ is for the people that want to know how does it work in the background. C# is for object-oriented programming beginners and for the Windows GUI programmers. I like programming and in the future I plan to programme C++. Maybe I make some new project.
(special thanks for my father AzazelDev)

Comments and Discussions

 
QuestionWhat about reference counting ? Pinmembercristitomi14-Mar-07 23:39 

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