Linker Error in c++, It is just a simple class program, I am beginner at c++
<pre><code>#include&lt;iostream&gt;
#include&lt;stdlib.h&gt;
#include"header_complex.h"

using namespace std;




class Complex
{
private:
 float real,imag;
public:
 Complex(); //default cnstructor
 Complex(float, float); //parametrize constructor
 void set_real(float);
 void set_imag(float);
 float get_real();
 float get_imag();
 void input();
 void display();

};


int main()
{
 Complex c1;  // object creation

 c1.display();
 c1.input();
 c1.display();

 return EXIT_SUCCESS;
}


//Functions definations

Complex::Complex(float a=0, float b=0)
{
  real = a;
  imag = b;
}

 void Complex::set_real(float a)
{
  a = real;
}

void Complex::set_imag(float a)
{
  a = imag;
}

float Complex::get_real()
{
  return real;
}
float Complex::get_imag()
{
  return imag;
}

void Complex::input(){
  cout &lt;&lt; "Enter Real part ";
  cin &gt;&gt; real;
  cout &lt;&lt; "Enter Imaginary part " ;
  cin &gt;&gt; imag;
}

void Complex::display()
{
  cout &lt;&lt; "Real part is  " &lt;&lt; real;
  cout &lt;&lt; "Imaginary part is  " &lt;&lt; imag;
}
</code></pre>
