Layout of user-define function
#include <iostream> using namespace std; int sum (); // essential part void main() { int result=sum(); // name a variable as the name of function (automatically the retuen value is save in it) cout<<"The result of additional is "<<result<<endl; // use the variable } int sum () // function name { int a=10; int b=10; int ans=a+b; return ans; // the value in answer can b use any where, where the function is call }