How to align a div in horizontally middle of the web page?
You have to provide a width to the div and make the left and right margin auto
What is a callback?
What is a pointer in C++?
A pointer is a variable that can store address of other variables. Pointer variables can be declared just like a normal variable but the datatype must have ' * ' as a after it. For eg int *P; here we have declared a pointer P that can stores address of an integer type variable. For eg int *P; int n=5; P=&n; // & is used to get the address of a variable. Here the address is being stored in a pointer