A callback is any executable code that is passed as an argument to another code, which is expected to call back (execute) the argument at a given time. In simple language, If a reference of a function is passed to another function as an argument to call it, then it will be called a Callback function.
In C, a callback function is a function that is called through a function pointer.
Below is a simple example in C to illustrate the above definition to make it more clear.
// A simple C program to demonstrate callback #include <stdio.h> void A(){
printf ( "I am function A\n" );
} // callback function void B( void (*ptr)())
{ (*ptr)(); // callback to A
} int main()
{ void (*ptr)() = &A;
// calling function B and passing
// address of the function A as argument
B(ptr);
return 0;
} |
I am function A
In C++ STL, functors are also used for this purpose.
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