Answer / zero zero....

• callback function is a function that is called
through a function pointer.
• pass the pointer (address) of a function as an
argument to another, when that pointer is used to call the
function it points to it is said that a call back is made.
// 2.1 define a function pointer and initialize to NULL
int (*pt2Function)(float, char, char) =
NULL; // C
int (TMyClass::*pt2Member)(float, char, char) =
NULL; // C++
int (TMyClass::*pt2ConstMember)(float, char, char) const =
NULL; // C++

• A callback function is a function that is passed
to another function (in the form of a pointer to the
callback function) so that the second function can
call it. This is simply of way of making the second
function more flexible without the second function needing
to know a lot of stuff

Uses:
• A callback can be used for notifications
• callback functions can be used for updates, sort of
like hooking into another function. For example, consider a
function that downloads files using http. Your application
may want to display progress to the user. You could pass a
callback function (display progress) into the download
function so that it calls your display function everytime
it reads from the socket. At least that is my
understanding...

Answer / manjula

a callback function is a function that is called through a
function pointer. If you pass the pointer (address) of a
function as an argument to another, when that pointer is
used to call the function it points to it is said that a
call back is made.

Answer / kishore kumar naik p

Call back functions are related to function pointers. To
understand this see the syntax of standard "qsort" below

void qsort(
void* base,
size_t num,
size_t width,
int (
__cdecl* compare
)(
const void* elem1,
const void* elem2
)
);
(refer MSDN for more info on "qsort")

In above syntax The fourth argument is function pointer.
So when we call this function we will send the address of
"Compare" function to "qsort" function and "Compare"
function will be called by the "qsort" depending on the
logic inside "qsort" function. In this case "Compare"
function is called back by the "qsort". So "Compare" is a
call back function here.

Answer / ravi

A callback function is a function that gets invoked by the
OS when the function having its pointer as one of its
arguments is invoked.

Answer / ratnesh sachan

Callback function is a function that is called through a
function pointer. If you pass the pointer(address) of a
function as an argument to another, when that pointer is
used to call the function it is point is said that a call
back is made...

#include<iostream.h>

int sachan(int a,int b)
{
printf("%d %d",a,b);
return 0;
}
main()
{
int(*abc)(int,int);
abc=&sachan;
abc(10,20
);
}

Answer / rahul

Its a function called by OS. This function is like telling
OS to convey about certain event or many events to your
program by calling this function.

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