object initialized to zero(not a pure virtual function)

[babu198649]

hi
i saw a program which inside its class initializes another class object to zero.
also if i initialize to some other number other than zero ,an error occurs.

Circle* cp = 0;

this is not related with pure virtual function since it is an object not a function.

can some one could explain what it is.

[scruggsy]

hi
i saw a program which inside its class initializes another class object to zero.
also if i initialize to some other number other than zero ,an error occurs.

Circle* cp = 0;

this is not related with pure virtual function since it is an object not a function.

can some one could explain what it is.

A pointer with a value of zero is called a null pointer; it means the pointer points to nothing.
In C++ it's more common to use Circle* cp = NULL; to make the intention more clear. Either way, pointers should always be initialized to NULL (or 0); otherwise they may point to garbage and produce difficult-to-find bugs.

[babu198649]

thanks......... ...........

[babu198649]

does pointing to 0(NULL) will not point to data in 0th location

[weaknessforcats]

Circle* cp = NULL;

This is C. There is no NULL in C++. Use 0.

[scruggsy]

This is C. There is no NULL in C++. Use 0.

Really? My mistake. Thanks.
In any case, babu, if you try to dereference a pointer with a value of 0, most operating systems generate an exception. If you dereference an uninitialized pointer, on the other hand, the OS can't tell that you've made a mistake, which makes the error much more difficult for you to track down.