Experience with C + + void*

Today in writing the project needs, use to void*, began not to understand what void* mean, asked the eldest, a language awakened dream of people!!!!!!

Event->setuserdata ((void*) 10);

int* data = (int*) event->getuserdata ();
Cclog ("data =%d", data);

Start so set Setuserdata, very puzzled why not *data can output 10, but *data on the error!!!!

The boss said, the value of the pointer itself is 10, I understand!!!!

(void*) 10 is to turn 10 into a pointer address value, this address is not initialized, so *data is basically wrong, the address value is 10 of this memory address content unknown!!!!

Later the boss said, direct int data = (int) event->getuserdata (); You can use the value of 10, as long as the compiler does not error!!!

In the group also asked this question, also get a solution, directly new out on OK, there will be no ambiguity!

Event->setuserdata (new int (10));

int* data = (int*) event->getuserdata ();

int b = *data;

Cclog ("&data =%d, data =%d", data, *data);

This can also use the value of 10!!!

Void* This previous use of less, do not understand!!!! Today is a rise in knowledge!!!!!!!

If it is an int type, it is convenient to use the first kind!!!!!

Thank you very much boss and group of Friends!!!!

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Experience with C + + void*