C++参数化构造函数

#include <iostream>

using namespace std;

class Line {
   public:
      void setLength( double len );
      double getLength( void );
      Line(double len);    // This is the constructor

   private:
      double length;
};

// Member functions definitions including constructor
Line::Line( double len) {
   cout << Object is being created, length =  << len << endl;
   length = len;
}
void Line::setLength( double len ) {
   length = len;
}
double Line::getLength( void ) {
   return length;
}

// Main function for the program
int main() {
   Line line(10.0);

   // get initially set length.
   cout << Length of line :  << line.getLength() <<endl;

   // set line length again
   line.setLength(6.0); 
   cout << Length of line :  << line.getLength() <<endl;

   return 0;
}