Function Prototype

[feehily]

#include<iostream>
using namespace std;

int welcome()
{
cout<<"\t\taggregation programn";
cout<<"2 integers "<<endl;
}

int result(int ,int )
{
int x, y;
return(x+y);
}

void input_value()
{

int x, y;
cout<<"first number :" ;
cin>>x;
cout<<"second number :" ;
cin>>y;
}

int main()
{
int x, y;
welcome();
input_value();

result(x,y);
cout<<x<<"+"<<y<<"="<<result(x,y);
}

why the program error? where mistakes?
somebody please help me

[firedraco]

Did you try compiling it? The compiler will tell you if there is an error and if so, where it is.

[wildblue]

Your welome() function thinks it should return an integer, but it doesn't. If it's just going to print out statements, it can be a void function instead of int.

Also - the x and y variables you define in each function are local to that particular function. You are passing all variables by value, not by reference, so changes one function does to x or y will not be reflected in another function. So in the main function when you pass x and y to the result function, you are sending uninitialized values.

You don't need to call result(x,y) separately before the cout statement at the end of main.

Edit: Scroll down on this page to the "Arguments passed by value and by reference" section for more info on passing variables by value vs. by reference.
http://www.cplusplus.com/doc/tutorial/functions/

[feehily]

program can be run, it's just that the results are wrong. The program does not add up properly

[feehily]

i dont understand about 'reference' that you mean, please correct at program script

[long double main]

The program does not add up properly

That's because the x and y in result and input_value are not the same x and y in main.

You can fix your result function by actually using the two parameters you gave it:

int result(int x, int y)
{
    return x+y;
}

Now, for your input_value function, you need the x and y in that function to be the same x and y that you declared in main (right now, they're completely separate from each other).
One way to do that is to pass them by reference:

void input_value(int& x, int& y)
{
    cout << "first number: ";
    cin >> x;
    // ... 

Then, to call input_value, you would write input_value(x, y); in main.

On a side note, your welcome function says that it returns an int, but it doesn't.
Also, you don't need to call result twice -- the first call doesn't magically "store" the result anywhere or anything like that.

[feehily]

thankyou