what is the difference between function declaration and signature?

Question

In C or C++ what is the difference between function declaration and function signature?

I know something of function declaration but function signature is totally ne

Answer 1

A function declaration is a prototype. A function signature indicates what is the return type and the parameters used that makes up the signature. Consider this:

int foo(int, int);  /* Function Declaration */


/* Implementation of foo 
** Function signature
*/
int foo(int a, int b){
}

Now, consider this scenario: a programmer is asked what is the function signature for foo:

• It returns a datatype of int
• Two parameters are also of datatype of int, named a and b respectively

The function prototype on the other hand is to clue in the C/C++ compiler, on what to expect and if the signature does not match up with the prototype, the compiler will emit an error, along the context of 'function declaration error' or 'prototype mismatch'.