A callback is any executable code that is passed as an argument to other code, which is expected to call back (execute) the argument at a given time [Source : Wiki]. 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 as 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
" ); } // 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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