CSCI 15A                                               Jim Murphy

In addition to the while loop C++ also has a 
for statement and a do...while construct

for (counter=initial; loop-test; repeated-statement)
{
iterative part
}

After the counter is initialized, the loop-test is
evaluated and if true the iterative-part is executed
and the repeated-statement is executed then the
loop-test is applied again - this continues until false

The code on page 281 shows that the counter could be
a float or any other type not just an int

 src/p281.cpp
// Declare and use a float for the counter of a for loop
#include <iostream.h>
#include <math.h>
#include "ourstuff.h"

float f(float x)
{
  return  x - cos(x);
}

int main()
{
  cout << endl << "   x   |   f(x) ";
  cout << endl << "------+--------" << endl;
  decimals(cout, 2);
  for(float x = 0;  x <= 2; x = x + 0.5)
  {
    cout.width(6);
    decimals(cout, 1);
    cout << x << " |";
    cout.width(7);
    decimals(cout, 4);
    cout << f(x) << endl;
  }
  return 0;
}

Execute with p281

   x   |   f(x)
------+--------
   0.0 |-1.0000
   0.5 |-0.3776
   1.0 | 0.4597
   1.5 | 1.4293
   2.0 | 2.4161

Page 282 shows code where the value used in the loop
test is passed as a parameter
 src/p282.cpp
// Call produceAverage to illustrate for loops need to
// know the number of repetitions before they are
// encountered in the program.

#include <iostream.h>

void produceAverage(int n)  // In: Number of floats to be 
averaged
{
  //  PRE: n > 0 and no bad input is encountered in cin
  // POST: n floats are entered from the keyboard
  // and averaged
  float ave;               // Average of n floats.
  float value, sum;// value: the input; sum:running sum.

  // Initialize sum to 0 to ensure the correct average
  sum = 0;
for(int counter = 1; counter <= n;counter = counter+ 1)
  {
    cout << "Enter number: ";
    cin >> value;
    sum = sum + value;
  }

  // Compute and display the average
  ave = sum / n;
  cout << "Average: " << ave;
}
int main()
{
  produceAverage(3);
  return 0;
}

Execute with: p282
Enter number: 57
Enter number: 38
Enter number: 76
Average: 57

C++ also provides an increment operator ++ and a
decrement operator -- which allows
counter = counter + 1; // to be replace with counter++;

for(counter=0; counter < 10; counter++)
   cout << counter << endl;

LESSON 13

The do while statement puts the test at the end:
do {
  iterative-part
   }  while (loop-test);

The iterative part always executes at least once
also the braces { and } are needed even for one line
iterative parts - particularly good when user input is
needed in the loop for initialization as on page 287

src/p287.cpp
// Page 287 code has been modified
#include <iostream.h>
#include"ourstuff.h"//for clearScreen and causeApause
#include <iomanip.h>   // for setw(32)
#include <ctype.h>     // for toupper(char)

void getTransaction(char & transaction)
{
  clearScreen();
  cout << "\n\n";
  cout << " ATM ----------------------------------------" 
          << endl;
  cout << setw(32) << "Withdraw [W]";
  cout << "\n";
  cout << setw(32) << " Deposit [D]";
  cout << "\n";
  cout << setw(32) << " Balance [B]";
  cout << "\n";
  cout << setw(32) << "    Quit [Q]";
  cout << "\n\n";

  // Currently any letter pressed will be returned
  // as its uppercase equivalent.  Only four choices
  // should be returned: w/W, d/D, b/B, and q/Q to quit

  do {
    cout << setw(30) << "Select [W,D,B,Q]: ";
    cin >> transaction;
    transaction = toupper(transaction);
  } while((transaction != 'W') &&
          (transaction != 'D') &&
          (transaction != 'B') &&
          (transaction != 'Q'));
}

int main()
{
   cout << "This program implements getTransaction" 
           << endl;
   cout << "as a free (non-member) function"<< endl;
   causeApause();

   char transaction;
   getTransaction(transaction);
   cout << endl << endl << "You entered '" 
           << transaction << "'" << endl;
}

Execute with: p287
This program implements getTransaction
as a free (non-member) function

. . . Press Enter to continue . . .



 ATM ----------------------------------------
                    Withdraw [W]
                     Deposit [D]
                     Balance [B]
                        Quit [Q]

            Select [W,D,B,Q]: B


You entered 'B'

Most repetition can be done with any of the three loop
constructs but usually one will be better than the others

If you know how many times you are going to loop
use the for statement - if you do not know the number
of repetitions but the loop must execute at least once
to initialize certain objects use the do while construct
If the test needs to be performed first before the code
will make sense use the while statement

Structured classes allow us to store several different
objects within one object as with the bankAccount
and ATM classes with name and PIN etc.
Arrays are structured classes which provide for 
collections of several objects of the same type
A generic declaration looks like:

class-name array-name [ int-expression ];

float  scores[92];
Which provides for up to 92 float type test scores

bankAccount  customer[200];
works just as well where each customer will have a
name, PIN and balance

dice::dice(unsigned seed)
dice list[20];
dice::dice()
{
r=g=1;
srand((unsigned)time(NULL));
}


We can refer to individual items in the collection with
scores[37] = 78;  or
x = 5*scores[37] + 12;
cout << "Test number " << n << " is " << scores[ n ];
n must be between 0 and 91 for this to work
int a2,a3,a4,a5,a6...,a12;
switch ( x=mydie.toss())
{
case 2:
    a2++;
    break;
case 3...

int a[11];
for(int x=0; x< 11; x++)
   a[x]=0;
 a[mydie.toss() - 2]++;
 count++;
 count = count + 1;
a[mydie.toss() - 2] = a[mydie.toss() - 2] + 1;
x=mydie.toss() - 2;
a[x] = a[x] +1;

int a[13];


If n is an integer then scores[n] can be used anyplace
that a float can be used and we can call member
functions for a bankAccount object such as:
cout << customer[8].name( ) << endl;
for ( int x=0,sum=0; x<92; x++)
       sum= sum + scores[x];
float average = sum/92.0;

src/p301-303.cpp
// This program is made up of the code from 
// pages 301 through 303
#include <iostream.h>
#include "ourstuff.h" // for decimals(cout, 2)
#include <iomanip.h>  // for setw(3)

int main()
{
  float floatArray[5];

  floatArray[0] = 12.6;
  floatArray[1] = 5.7;
  floatArray[2] = floatArray[0] + floatArray[1];  
              // Store 18.3

  cout << "To match book, enter these two float values: 
9.99 15.0 " << endl;
  cin >> floatArray[3] >> floatArray[4];

  int j;
  decimals(cout, 2);
  cout << "All 5 Elements of floatArray: " << endl;
  for(j = 0; j < 5; j++)
    cout << j << ':' << setw(6) << floatArray[j] << endl;

  // Let the first element be the largest
  float largest = floatArray[0];
  // Now compare the other array elements
  for(j = 1; j < 5; j++)
  {
    if(floatArray[j] > largest)
      largest = floatArray[j];
  }
  cout << "The largest floatArray element = " 
           << largest;

  return 0;
}
 p301-303
To match book, enter these two float values: 9.99 15.0
9.99 15.0
All 5 Elements of floatArray:
0: 12.60
1:  5.70
2: 18.30
3:  9.99
4: 15.00
The largest floatArray element = 18.30
float scores[92];
Note that scores[92] is not part of the array and that
scores[92] = 37; // will not cause a compiler error
but will alter some value in memory that should not
be changed - which will most likely cause a problem
in your program - check that you are within range
src/p305-307.cpp
// This program illustrates arrays of 
// programmer defined objects.
#include <iostream.h>
#include "ouracct.h"   // for class bankAccount
#include "ourstuff.h"  // added for decimals
int main()
{
  int j;
  // Declare
  bankAccount customer[3];
  customer[0] = bankAccount("Hall", "1234", 100);
  customer[1] = bankAccount("Small", "4321", 0);
  customer[2] =
     bankAccount("Ewall","1082", 10000.00);
  cout << "Show the three elements of customer: "
           << endl;
  for(j = 0; j < 3; j ++)
    cout << "customer[" << j << "]: " 
            << customer[j] << endl;
  cout << endl;
  for(j = 0; j < 3; j ++)
    cout << customer[j].name() << endl;

  cout << endl;
  float sum = 0.0;
  for(j = 0; j < 3; j++)
    sum = sum + customer[j].balance();

  decimals(cout, 2);
  cout << "The total balance is: " << sum << endl;

  return 0;
}
int Old = 0, New = 1;
customer[New].deposit( customer[Old].balance() );

p305-307
Show the three elements of customer:
customer[0]: { bankAccount: HALL, 1234, 100.00 }
customer[1]: { bankAccount: SMALL, 4321, 0.00 }
customer[2]: { bankAccount: EWALL, 1082, 10000.00 }

HALL
SMALL
EWALL

The total balance is: 10100.00

The program on pages 308 and 309 shows how to read
data from a file of bank accounts into an array of
bank accounts as is maintained by an object of the
bank class earlier - this code also checks the range
on the index of the array to make sure we do not
write beyond the memory set aside for our list of
bank accounts in customer
We also generate the number of customers in the
process of reading them in from the data file


src/p309.cpp
// Initialize an array of bankAccount objects through
// file input. The file stores sixteen (16) customers. 
// The first bankAccount object is stored in 
// customer[0] and the 16th is stored as customer[15].

#include <fstream.h>  // for class ifstream
#include "ouracct.h"  // for class bankAccount

int main()
{ //  PRE: The input file 'bank.dat' is in the proper 
// directory, has valid format, and has no extraneous
//  lines at the end
  // POST: An array of bankAccount objects and the
// number of customers stored in the file bank.dat 
// are set

  ifstream inFile("bank.dat");
  if(! inFile)
    cout << "**Error** The file 'bank.dat' was not opened" 
<< endl;
  else
  {
    const int MAX_CUSTOMERS = 20;
    bankAccount customer[MAX_CUSTOMERS];
    string name, PIN;
    float balance;
    int numberOfCustomers = 0;

    while( (numberOfCustomers <MAX_CUSTOMERS)
                 && (!inFile.eof()) )
    {
      inFile >> name >> PIN >> balance;
      // Go to next line or make eof true
      inFile.ignore(80, '\n');
      customer[numberOfCustomers] = 
                   bankAccount(name, PIN, balance);
      numberOfCustomers++;
    }

    // Antibugging tip: It is good practice to verify 
    // that an array is properly initialized!
    // The numberOfCustomers is very important as is
    // the data stored at each array element. So first
    // output numberOfCustomers.  Then display # 
    // each bankAccount object with cout <<.
    cout << "Number of customers on file: " 
            << numberOfCustomers << endl;
    cout << endl;
    cout << "             The customers"           << endl;
    cout 
<< "=================================" 
<< endl;
    for(int j = 0; j < numberOfCustomers; j++)
      cout << j << ". " << customer[j] << endl;
  } // end else
  return 0;
}
p309
Number of customers on file: 20

             The customers
   =================================
0. { bankAccount: CUST0, 0000, 0.00 }
1. { bankAccount: YOURLASTNAME, ANY4, 111.11 }
2. { bankAccount: AUSTEN, 2222, 222.22 }
3. { bankAccount: CHELSEA, 3333, 333.33 }
4. { bankAccount: CUST4, 4444, 444.44 }
5. { bankAccount: CUST5, 5555, 555.55 }
6. { bankAccount: CUST6, 6666, 666.66 }
7. { bankAccount: CUST7, 7777, 777.77 }
8. { bankAccount: CUST8, 8888, 888.88 }
9. { bankAccount: CUST9, 9999, 999.99 }
10. { bankAccount: CUST10, 1010, 1010.10 }
11. { bankAccount: CUST11, 1111, 1111.11 }
12. { bankAccount: CUST12, 1212, 1212.12 }
13. { bankAccount: CUST13, 1313, 1313.13 }
14. { bankAccount: CUST14, 1414, 1414.14 }
15. { bankAccount: HALL, 1234, 100.00 }
16. { bankAccount: CUST16, 1010, 1010.10 }
17. { bankAccount: CUST17, 1111, 1111.11 }
18. { bankAccount: CUST18, 1212, 1212.12 }
19. { bankAccount: CUST19, 1313, 1313.13 }

cat src/bank.dat
Cust0        0000 000.00
YourLastName ANY4 111.11
Austen       2222 222.22
Chelsea      3333 333.33
Cust4        4444 444.44
Cust5        5555 555.55
Cust6        6666 666.66
Cust7        7777 777.77
Cust8        8888 888.88
Cust9        9999 999.99
Cust10       1010 1010.10
Cust11       1111 1111.11
Cust12       1212 1212.12
Cust13       1313 1313.13
Cust14       1414 1414.14
Hall         1234 100.00
Cust16       1010 1010.10
Cust17       1111 1111.11
Cust18       1212 1212.12
Cust19       1313 1313.13
Cust20       1010 1010.10
Cust21       1111 1111.11
Cust22       1212 1212.12
Cust23       1313 1313.13
Cust24       1414 1414.14