Incremental Programming

Read three integers and display the difference between the largest and the smallest values.  

The sequence of programs will be:

1. P0:   Read and echo three integers.
   
2. P1:   Same as P0,  plus determine and display the maximum value.
   
3. P2:   Same as P1,  plus determine and display the minimum value.
   
4. P3:   Same as P2,  plus compute and display the difference between the max and min values.
   
5. P4:   Same as P3,  but delete all ``extra'' output.
   

P0:  

static public void main (String args [])   {   / /Read and echo two integers.       int a = IO.read_int ();       int b = IO.read_int ();       IO.println (``a =  ``+ a);       IO.println (``b =  ``+ b);

 

P1:  

static public void main (String args [])   {   / /Read and echo two integers.       int a = IO.read_int ();       int b = IO.read_int ();       IO.println (``a =  ``+ a);       IO.println (``b =  ``+ b);     / /Compute and print the max value.       int max = max (a,  b);       IO.println (max);   }   static private int max (int a,  int b)   {       if (a > b)       {         return a;       }       else       {         return b;       }       }

 

P2  

static public void main (String args [])   {   / /Read and echo two integers.       int a = IO.read_int ();       int b = IO.read_int ();       IO.println (``a =  ``+ a);       IO.println (``b =  ``+ b);     / /Compute and print the max value.       int max = max (a,  b);       IO.println (max);   }   static private int max (int a,  int b)   {       if (a > b)       {         return a;       }       else       {         return b;       }       }     / /Compute and print the min value.       int min = min (a,  b);       IO.println (``min =  ``+ min);   }   static private int min (int a,  int b)   {       if (a > b)       {       return b;       } \ttline       {       return a;       }   }

 

P3  

static public void main (String args [])   {   / /Read and echo two integers.       int a = IO.read_int ();       int b = IO.read_int ();       IO.println (``a =  ``+ a);       IO.println (``b =  ``+ b);     / /Compute and print the max value.       int max = max (a,  b);       IO.println (max);   }   static private int max (int a,  int b)   {       if (a > b)       {         return a;       }       else       {         return b;       }       }     / /Compute and print the min value.       int min = min (a,  b);       IO.println (``min =  ``+ min);   }   static private int min (int a,  int b)   {       if (a > b)       {       return b;       }       else       {       return a;       }   }     / /Compute and display difference.       int diff = max - min;       IO.println (``diff =  ``+ diff);   }

 

P4  

static public void main (String args [])   {   / /Read and echo two integers.       int a = IO.read_int ();       int b = IO.read_int ();     / /Compute and print the max value.       int max = max (a,  b);   }   static private int max (int a,  int b)   {       if (a > b)       {         return a;       }       else       {         return b;       }       }     / /Compute and print the min value.       int min = min (a,  b);   }   static private int min (int a,  int b)   {       if (a > b)       {       return b;       }       else       {       return a;       }   }     / /Compute and display difference.       int diff = max - min;       IO.println (``diff =  ``+ diff);   }

 

PROBLEM  

Read several (at least one) non negative integers and compute their real average.  

?   Program     {   / /Establish an ``accumulator.''       int sum = 0;     / /Establish a counter to count data.       int count = 0;     / /Sum the integers.       int num = IO.read_int ();       while (num > = 0)       {         sum = sum + num;         count = count + 1;         num = IO.read_int ();       }     / /Compute and display the average.       double ave = (double) sum / (double) count;       IO.println (``ave =  ``+ ave);   }