Notes
Outline
switch Statement Example
   int alpha = 0; int beta = 0; int gamma = 0;  int n;
   cout << "Please enter a value of n for processing " << endl;
   cin >> n;
   cout << " The value you entered for n is " << n << endl;
   switch(n)
   {
      case 3:  alpha++;
               break;
      case 7:  beta++;
               break;
      case 10: gamma++;
               break;
   }
   cout << "alpha is " << alpha << endl << "beta is " << beta
        << endl  << "gamma is " << gamma << endl;
}
Loop Example
#include <iostream>
using namespace std;
int main()
{
   int sum;
   int count;
   sum = 0;
   count = 1;
   while (count <= 1000)
   {
      sum = sum + count;
      count++;
   }
   cout << " The final sum is " << sum << endl;
}
Equivalent for Statement
#include <iostream>
using namespace std;
int main()
{
   int sum;
   int count;
   sum = 0;
   for (count = 1; count <= 1000; count++)
      sum = sum + count;
   cout << " The final sum is " << sum << endl;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 4
   {
      for (j = 0; j < i; j++)
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 4
   {
      for (j = 0; j < i; j++) j = 0
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 4
   {
      for (j = 0; j < i; j++) j = 0
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 4
   {
      for (j = 0; j < i; j++) j = 1
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 4
   {
      for (j = 0; j < i; j++) j = 1
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 4
   {
      for (j = 0; j < i; j++) j = 2
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 4
   {
      for (j = 0; j < i; j++) j = 2
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 4
   {
      for (j = 0; j < i; j++) j = 3
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 4
   {
      for (j = 0; j < i; j++) j = 3
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 4
   {
      for (j = 0; j < i; j++) j = 4
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 4
   {
      for (j = 0; j < i; j++) j = 4
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 3
   {
      for (j = 0; j < i; j++) j = 4
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 3
   {
      for (j = 0; j < i; j++) j = 0
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 3
   {
      for (j = 0; j < i; j++) j = 0
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 3
   {
      for (j = 0; j < i; j++) j = 1
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 3
   {
      for (j = 0; j < i; j++) j = 1
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 3
   {
      for (j = 0; j < i; j++) j = 2
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 3
   {
      for (j = 0; j < i; j++) j = 2
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 3
   {
      for (j = 0; j < i; j++) j = 3
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 3
   {
      for (j = 0; j < i; j++) j = 3
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 2
   {
      for (j = 0; j < i; j++) j = 3
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 2
   {
      for (j = 0; j < i; j++) j = 0
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 2
   {
      for (j = 0; j < i; j++) j = 0
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 2
   {
      for (j = 0; j < i; j++) j = 1
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 2
   {
      for (j = 0; j < i; j++) j = 1
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 2
   {
      for (j = 0; j < i; j++) j = 2
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 2
   {
      for (j = 0; j < i; j++) j = 2
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 1
   {
      for (j = 0; j < i; j++) j = 2
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 1
   {
      for (j = 0; j < i; j++) j = 0
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 1
   {
      for (j = 0; j < i; j++) j = 0
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 1
   {
      for (j = 0; j < i; j++) j = 1
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 1
   {
      for (j = 0; j < i; j++) j = 1
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 0
   {
      for (j = 0; j < i; j++) j = 1
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
Nested for Example
#include <iostream>
using namespace std;
int main()
{
int i;
int j;
for (i = 4; i >= 1; i--) i = 0
   {
      for (j = 0; j < i; j++) j = 1
         cout << j << "***";
      cout << i << endl;
   }
   return 0;
}
do-while Statement Example
int main()
{
   int num; int count = 0; int sum = 0;
   do
   {
      cout << "Please enter a number for summing " << endl;
      cin >> num;
      if (num > 0)
      {
         sum = sum + num;
         count++;
         cout << "The number is " << num << endl;
      }
   } while ((num > 0) && (count < 10));
   cout << "The sum is " << sum << endl;
}
Problem Solving Case Study
Problem: Write an interactive program to enter 12 rainfall values for as many sites as the user wishes, averaging the 12 for each site.
Input: 12 rainfall amounts (float) for each site, ‘y’ or ‘n’ answer to prompt for continuing (char)
Problem Solving Case Study
Outputs: The average (float) for each site, displayed to two decimal places.
Discussion: Several loops are required: one to process the data from all sites, one to sum the 12 values at each site, two more loops for data validation
Assumption: The user processes data for at least one site.
Problem Solving Case Study
//************************************************************
// Rainfall program
// This program inputs 12 monthly rainfall amounts from a
// recording site and computes the average monthly rainfall.
// This process is repeated for as many recording sites as
// the user wishes.
//************************************************************
#include <iostream>
#include <iomanip>    // For setprecision()
using namespace std;
void Get12Amounts( float& );
void GetOneAmount( float& );
void GetYesOrNo( char& );
Problem Solving Case Study
int main()
{
    float sum;           // Sum of 12 rainfall amounts
    char  response;      // User response ('y' or 'n')
    cout << fixed << showpoint          // Set up floating pt.
         << setprecision(2);            //   output format
    do
    {
        Get12Amounts(sum);
        cout << endl << "Average rainfall is " << sum / 12.0
             << " inches" << endl << endl;
        cout << "Do you have another recording site? (y or n) ";
        GetYesOrNo(response);
    } while (response == 'y');
    return 0;
}
Problem Solving Case Study
void Get12Amounts( /*out*/ float& sum ) // Sum of rainfall
// Inputs 12 monthly rainfall amounts, verifying that
// each is nonnegative, and returns their sum
// Postcondition:
//     12 nonnegative rainfall amounts have been read
//  && sum == sum of the 12 input values
{
    int   count;       // Loop control variable
    float amount;      // Rainfall amount for one month
    sum = 0;
    for (count = 1; count <= 12; count++)
    {
        cout << "Enter rainfall amount " << count << ": ";
        GetOneAmount(amount);
        sum = sum + amount;
    }
}
Problem Solving Case Study
void GetYesOrNo( /*out*/ char& response )  // User response char
// Inputs a character from the user and, if necessary,
// repeatedly prints an error message and inputs another
// character if the character isn't 'y' or 'n'
// Postcondition:
//     response has been input (repeatedly, if necessary, along
//     with output of an error message)
//  && response == 'y' or 'n‘
{
    do
    {
        cin >> response;
        if (response != 'y' && response != 'n')
            cout << "Please type y or n: ";
    } while (response != 'y' && response != 'n');
}
Problem Solving Case Study
void GetOneAmount( /*out*/ float& amount )   // Rainfall amount
                                             // for one month
// Inputs one month's rainfall amount and, if necessary,
// repeatedly prints an error message and inputs another
// value if the value is negative
// Postcondition:
//     amount has been input (repeatedly, if necessary, along
//     with output of an error message)
//  && amount >= 0.0
{
    do
    {
        cin >> amount;
        if (amount < 0.0)
            cout << "Amount cannot be negative. Enter again: ";
    } while (amount < 0.0);
}