For the cat, the function `sound()` declaration and call will look:

```
#include <iostream>
using namespace std;

// Function declaration
void sound() {
    cout << "meow!" << endl;
}

int main() {
    // Call the function to be executed 
    sound();

    return 0;
}
```

Remember:
- you have to declare a function before calling it.  
- you can declare the function as many times as you want.

You have met functions at the beginning of your C++ programming path. `main()` - is the pre-defined function that is used to execute the code.

Every program in c++ contains the function:

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Declaration

1. You have to...

2. Every program in c++ contains the function: