Pointers, dynamic variables, C++ - c++

Question

Errors
I keep receiving errors when running this program. What do these errors mean? A screenshot is attached.
This is the problem:
A class Area that has two private variable members; units of type string and area_value of type float.
1) Input from the keyboard the area_value and its units. Compute one-half and one-quarter of the area and display the results with unit.
2) Destroy the dynamic variable at the end.
#include <iostream
#include <string>
using namespace std;
class Area
{
public:
Area();
void setu(string a);
void seta(float b);
string getu();
float geta();
private:
string unit;
float area_value;
};
int main()
{
Area *p = new Area();
string a;
float f;
cout << "Enter a unit with no space: ";
getline(cin, a);
p->setu(a);
cout << "Enter a value of area: ";
cin >> f;
p->seta(f);
cout << "A half of your input = " << f / 2 << endl;
cout << "A quarter of your input = " << f / 4 << endl;
delete p;
return 0;
}

Answer 1

Looks like
You have not implemented the member functions, or
You have implemented the member functions in a separate file and forgot to include it in building the executable.

Answer 2

It seems you forgot to implement the constructor Area() and the methods of your Area class.

Answer 3

The first include is missing greater than sign (>). The public Area class only defines the functions, not implementing them. Variable p is defined as a pointer.
You can also add half and quarter as functions. I modified it slightly so it compiles with clang++ -Wall -std=c++11 -o area area.cpp.
#include <iostream>
#include <string>
using namespace std;
class Area {
public:
Area() {};
~Area() {};
void setu(string u) { unit = u; }
void seta(float a) { area_value = a; }
string getu() { return unit; }
float geta() { return area_value; }
float getHalf() { return area_value / 2; }
float getQuarter() { return area_value / 4; }
private:
string unit;
float area_value;
};
int main() {
Area p {};
string a;
float f;
cout << "Enter a unit with no space: ";
getline(cin, a);
p.setu(a);
cout << "Enter a value of area: ";
cin >> f;
p.seta(f);
cout << "A half of your input = " << p.getHalf() << endl;
cout << "A quarter of your input = " << p.getQuarter() << endl;
return 0;
}