Be Stingy With Variables

• Class member variables are like globals.

  • Member functions access them without the dot.

  • They retain their value between member function calls.

• class jackrabbit_ecology {
  
    private:
  
      int start, max, startold, startnew, count, rabbit_pop;
  
    public:
  
      int seasons(void) {
        while (rabbit_pop < max) {
          if (count == 0) startold = 1;
          startnew = rabbit_pop + startold;
          startold = rabbit_pop;
          rabbit_pop = startnew;
          count++
          }
        }
  
      int population(int i) {
        if (i > count) return 0;
        int rabbit_pop = start;
        for (int x = 0; x < i; x++) {
          startnew = rabbit_pop + startold;
          startold = rabbit_pop;
  	rabbit_pop = startnew;
          }
        return rabbit_pop;
        }
    }
  

Remember The Point

• If we talk about it,

• and then have a design test on it,

• and then have a lab test on it,

• your answer should involve it to get a good grade.

Design and Develop Piece by Piece

• Make sure you always have something you can compile.

• Once your code compiles, add new code piece by piece.

  1. class jackrabbit_ecology {
       };
     
     int main() {
       jackrabbit_ecology jre1, jre2;
       }
       

  2. class jackrabbit_ecology {
       public:
         jackrabbit_ecology(int s, int m) { }
       };
     
     int main() {
       jackrabbit_ecology jre1(7, 128), jre2(51, 1024);
       }
       

  3. #include <iostream>
     
     class jackrabbit_ecology {
       public:
         jackrabbit_ecology(int s, int m) { }
         int seasons(void) { return 0; }
       };
     
     int main() {
       jackrabbit_ecology jre1(7, 128), jre2(51, 1024);
     
       if (jre1.seasons() > jre2.seasons())
         cout << "first\n";
       else
         cout << "second\n";
       }
       

Learn the Syntax

• You must learn the basic syntax.

  Public:

  if seasons(Fst.start, Fst.max > seasons(Snd.start, Snd.max);

  int population(seasons) {

  if (i < 0) return 0;
int k = 1;
else
while ((k < i) && (p2 < max)) {

• You can't learn syntax by reading about it, or hearing about it.

  • You must read and listen and write programs.

This page last modified on 20 June 2001.