[C++] how to convert dec to hex?

I need to convert a decimal integer into hex.
The decimal integer is the value of a pointer and i need to get in hex to use it as a address for writeprocessmemory.
So is there any way to convert a dec into a hex and use the hex value as a argument for writeprocessmemory?

EDIT:meeh...forgot that the value is only displayed as decimal number -.-
/close plz

#closed