Error Code Debugging for C++ CodeBlocks

Question

I keep getting an error message in CodeBlocks it says:

Error: 'Addnumbers' was not declared in this scope

I just started with C++ and have no idea what this means. Here is my code:

#include <iostream>
using namespace std;

int main()
{
    int fnum;
    int snum;

    cout << "Enter First number" << endl;
    cin >> fnum;
    cout << "Enter Second Number" << endl;
    cin >> snum;

    Addnumbers (fnum, snum);
    return 0;
}

int Addnumbers(int fnum, int snum){
    int ans = fnum+snum;
    return ans;
}

Some programmer dude · Accepted Answer · 2013-05-03 21:21:34Z

2

You need to declare the function before it's used:

int Addnumbers(int fnum, int snum);

int main()
{
}

int Addnumbers(int fnum, int snum)
{
    // ...
}

The first declaration is what is called a prototype, and tells the compiler that somewhere there is a function named AddNumbers with the specified arguments and return type. Then you can have the definition anywhere, even in another source file.

In C++ (as well as in C or other languages base on C) everything must be declared before it it used. That's how the compiler will know that stuff exists.

edited May 3, 2013 at 21:21

answered May 3, 2013 at 21:10

Some programmer dude

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2 Comments

Fouroh3 Over a year ago

Thanks A lot! I didn't know. Is this the same for all function? is the Main function ALWAYS last?

Some programmer dude Over a year ago

@Col1107 Like in my example, the declaration can be before the main function, they just have to be before they are used. However, placing main last is almost always a safe bet.

user1508519 · Accepted Answer · 2013-05-03 21:11:12Z

1

You need to either move Addnumbers before main, or to do a forward declaration:

#include <iostream>
using namespace std;

int Addnumbers(int fnum, int snum);

int main()
{

answered May 3, 2013 at 21:11

user1508519

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