how to reference 3 functions while using struct - c++

Question

//I want to use 3 functions here with 1 struct that one function do the input
and one for calculation and the other one for out put but
I don't know how to reference //the variables in functions rec2 and rec3. I want to do it without using pointer
struct rectangle {
float length;
float width;
float area,perimeter;
};
rectangle rec1();
rectangle rec2();
rectangle rec3();
int main(){
rectangle f;
f = rec1();
f=rec2();
f = rec3();
return 0;
}
rectangle rec1(){
rectangle h;
cout<<"insert the length: ";
cin>>h.length;
cout<<"\ninsert width: ";
cin>>h.width;
return h;
}
rectangle rec2(){
rectangle z;
z.area=z.length*z.width;
z.perimeter=2*(z.length+z.width);
return z;
}
rectangle rec3(){
rectangle x;
cout<<"\narea is: "<<x.area<<endl<<"perimeter is: "<<x.perimeter<<endl;
return x;
}

Answer 1

You need to add methods to your rectangle struct.
struct rectangle
{
float length, width, area, perimeter;
void Input()
{
cout << "insert the length: ";
cin >> length;
cout << "\ninsert width: ";
cin>> width;
}
void Process(); // etc
void Output(); // etc
};
// Create a rectangle object and call it's methods
int main()
{
rectangle r;
r.Input();
r.Process();
r.Output()
}
The methods can now reference the member variables of the struct.

Answer 2

I suggest you change your design.
Place the input, process and output functions as methods inside the rectangle structure.
Placing the functions inside the structure allows them to access the data members.

Answer 3

Every time you return a new rectangle and assign it to your f variable, you are overwriting all of f's members, not just the ones you modified inside the function. You need to change the functions to modify f directly instead. You don't have to use a pointer for that, you can use a reference instead:
struct rectangle {
float length;
float width;
float area, perimeter;
};
void rec1(rectangle&);
void rec2(rectangle&);
void rec3(rectangle&);
int main(){
rectangle f;
rec1(f);
rec2(f);
rec3(f);
return 0;
}
void rec1(rectangle &r){
cout << "insert the length: ";
cin >> r.length;
cout << endl << "insert width: ";
cin >> r.width;
}
void rec2(rectangle &r){
r.area = r.length * r.width;
r.perimeter = 2 * (r.length + r.width);
}
void rec3(rectangle &r){
cout << endl << "area is: " << r.area << endl << "perimeter is: " << r.perimeter << endl;
}
But, this is C++ we are talking about, afterall. Member methods are your friends :)
struct rectangle {
float length;
float width;
float area, perimeter;
void rec1();
void rec2();
void rec3();
};
void rectangle::rec1(){
cout << "insert the length: ";
cin >> length;
cout << endl << "insert width: ";
cin >> width;
}
void rectangle::rec2(){
area = length * width;
perimeter = 2 * (length + width);
}
void rectangle::rec3(){
cout << endl << "area is: " << area << endl << "perimeter is: " << perimeter << endl;
}
int main(){
rectangle f;
f.rec1();
f.rec2();
f.rec3();
return 0;
}