Doubt: Before Calling Function,It should not declared If Advance Compiler changing function concepts please tell me

Question

Instead of Function Declaration We can define the function definition global definition

Answer 1

You always have to declare a function before the main()-function so that the compiler and linker know what they have to call during program execution. But you can defer a functions definiton (the body of a function) after main(). This is called forward declaration of functions.

#include <iostream>

void foo();

int main() {
foo();
}

void foo() {
std::cout << "body to forward-declared function which is defined after main" << std::endl;
}