error: ‘Namefunction’ was not declared in this scope - c++

Question

I am new to C++ and I had problems with running this small example of inputing number of rectangle that we want to calculate the area each every one of them.
Here is my code:
#include<iostream>
#include<conio.h>
using namespace std;
class Rectangle{
private:
float length;
float width;
public:
void input()
{
cout<<"length:"<<endl; cin>>length;
cout<<"width:"<<endl; cin>>width;
}
void output()
{
cout<<length<<"\t"<<width<<"\t"<<area();
}
void inputAll(Rectangle a[],int n)
{
for(int i=0;i<n;i++)
{
cout<<"Rectangle"<<(i+1)<<":"<<endl;
a[i].input();
}
}
void outputAll(Rectangle a[],int n)
{
for(int i=0;i<n;i++)
{
a[i].output();
}
}
float area()
{
return length*width;
}
};
int main()
{
Rectangle a[30];
int n;
cout<<"input n:"; cin>>n;
cout<<"Input all Rectangle data:"<<endl;
a.inputAll(a,n);
cout<<"Output all Rectangle data:"<<endl;
a.outputAll(a,n);
return 0;
}
Actually here are the errors in function inputAll and outputAll
main.cpp: In function ‘int main()’:
main.cpp:61:5: error: request for member ‘inputAll’ in ‘a’, which is of non-class type ‘Rectangle [30]’
a.inputAll(a,n);
^~~~~~~~
main.cpp:63:5: error: request for member ‘outputAll’ in ‘a’, which is of non-class type ‘Rectangle [30]’
a.outputAll(a,n);
^~~~~~~~~
I really dont know what caused the errors. Any help for this would be appreciated!

Answer 1

Member functions must be called using the dot. You'll have to loop over your objects:
int main()
{
Rectangle a[30];
int n;
cout<<"input n:"; cin>>n;
cout<<"Input all Rectangle data:"<<endl;
for (auto& r : a) {
r.inputAll(a,n);
}
cout<<"Output all Rectangle data:"<<endl;
for (auto& r : a) {
r.outputAll(n);
}
return 0;
}
Obviously, it doesn't make sense since you're already looping in those functions. You probably meant inputAll and outputAll to be free functions:
class Rectangle{
private:
float length;
float width;
public:
void input()
{
cout<<"length:"<<endl; cin>>length;
cout<<"width:"<<endl; cin>>width;
}
void output()
{
cout<<length<<"\t"<<width<<"\t"<<area();
}
float area()
{
return length*width;
}
};
void inputAll(Rectangle a[],int n)
{
for(int i=0;i<n;i++)
{
cout<<"Rectangle"<<(i+1)<<":"<<endl;
a[i].input();
}
}
void outputAll(Rectangle a[],int n)
{
for(int i=0;i<n;i++)
{
a[i].output();
}
}
With this simple change, your previous main function will work.

Answer 2

inputAll() is a member function of the Rectangle class. Please access the inputAll() through a object of the Rectangle class.