1. CS 1430: Programming in C++
No time to cover HiC

2. Quiz2-2
1. For each statement in the following, determine if it’s valid or invalid. (Circle your answers.)
float rate, hours, wage;
cin >> rate >> hours;
rate * hours = wage;
wage = rate * hours;
cout >> “The wage is ” >> wage;
cout << “The wage is ” << wage;
// Valid Invalid

3. Quiz2-2
2. What integer value does the following byte represent? 102 Assume the above byte represents ASCII character ‘f’. Gave the byte representing ASCII character ‘c’. 99 1 1

4. Quiz2-2 3. Evaluate the following mathematical expressions in C++:
15 / 8
19 % 33
/ 3 * 2
6 + 4 * 2
6 + 8
Result 1 19 14

5. Quiz2-2 4. Write C++ statements according to the comments.
// Declare float variables price and cost,
// and integer variable quantity
float price, cost;
int quantity;
// Input price with an input prompt
cout << “Enter the price: ”;
cin >> price;
// Input quantity with an input prompt
cout << “Enter the quantity: ”;
cin >> quantity;

6. Quiz2-2 4. Write C++ statements according to the comments.
// If price is positive and quantity is not negative,
// Compute cost, which is the product of price
// and quantity
// Display cost at the beginning of next line with
// message “The cost is ”
// Otherwise, display message “Invalid input!”
  if ( price > 0 && quantity >=0) {
cost = price * quantity;
cout << endl << “The cost is ” << cost; }
else
cout << endl << “Invalid input!”;

7. Quiz2-2 4. Write C++ statements according to the comments.
// Display cost at the beginning of next line with
// message “The cost is ”
cout << endl << “The cost is ” << cost;
cout << ‘\n’ << “The cost is ” << cost;
cout << “\n” << “The cost is ” << cost;
cout << “\nThe cost is ” << cost;

8. Sentinel-Controlled Loop
const int END_VALUE = -1; // not required const int LOW_LIMIT = 0; // not required const int HIGH_LIMIT = 60; int main() { int score, max; max = LOW_LIMIT; // Range is known cin >> score; // Prime read while (score != END_VALUE) if (score >= LOW_LIMIT && score <= HIGH_LIMIT) if (score > max) max = score; } else cout << “Invalid score!”; cin >> score; cout << “The max score is ” << max << ‘.’; return 0;

9. Sentinel-Controlled Loop
const int END_VALUE = -1; // not required const int LOW_LIMIT = 0; // not required const int HIGH_LIMIT = 60; int main() { int score, max; max = 0; // Range is known cin >> score; // Prime read while (score != -1) if (score >= 0 && score <= 60) // 0.5 points off on Prog1! if (score > max) max = score; } else cout << “Invalid score!”; cin >> score; cout << “The max score is ” << max << ‘.’; return 0;

10. Loop Control Variable (LCV)
while (score != -1) { … }
LCV: score
When to exit a loop
Avoid infinite loops

11. Four Parts of Loops Loop Initialization (LCV and others) Testing LCV
Loop Body
Updating LCV

12. While Loop Initialization (LCV and others) while (LogicalExpression)
(Testing LCV)
false
true
Do Work
Update LCV
Statement after loop

13. Four Parts of Loops
max = LOW_LIMIT; // Range is known cin >> score; // Prime read while (score != -1) { if (score >= LOW_LIMIT && score <= HIGH_LIMIT) if (score > max) max = score; } else cout << “Invalid score!”; cin >> score; cout << “The max score is ” << max << “.”;

14. Computing Count Range is not Known int score, max, count;
count = 0; // initialization
// cannot initialize max, since range unknown
cin >> score; // Prime Read
while (score != -1) {
count ++; // count = count + 1;
if (count == 1) // first score
max = score;
else
if (score > max) }
cin >> score;
if (count == 0)
cout << “No scores!”;
cout << “The maximal score is ” << max;

15. Computing Count Range is not Known int score, max, count;
cin >> score; // Prime Read
while (score != -1) {
count ++; // count = count + 1;
if (count == 1) // first score
max = score;
else
if (score > max) }
cin >> score;
if (count == 0)
cout << “No scores!”;
cout << “The maximal score is ” << max;
// Does it run?
// Run time error!
// Uninitialized value: count!

16. Computing Count Range is not Known int score, max, count;
count = 0; // Initialization!
cin >> score;
while (score != -1) {
count ++;
if (count == 1)
max = score;
else
if (score > max) }
if (count == 0)
cout << “No scores!”;
cout << “The maximal score is ” << max;
// Works even there is no score

17. Trace in Visual Studio Project CS1430Trace Trace-RangeUnkown.cpp
Trace-RangeKnown.cpp
Line/Column number
Break Point
Step Over
Reset
Auto/Locals
AutoHide

18. Trace Execution on Paper
Range unknown
int score, max, count;
count = 0;
cin >> score;
while (score != -1) {
count ++;
if (count == 1)
max = score;
else
if (score > max) }
if (count == 0)
cout << “No scores!”;
cout << “The maximal score is ” << max;
Input Scores: score max count ? ? ?

19. Tracing on Paper Range Known Tracing Input: 48 54 66 53 59 -1
const int LOW_LIMIT = 0;
const int HIGH_LIMIT = 60;
int score, max = LOW_LIMIT;
cin >> score;
while (score != -1) {
if (score < LOW_LIMIT ||
score > HIGH_LIMIT)
cout << “Invalid score: ”
<< score;
else
if (score > max)
max = score; }
Tracing
Input:
score max ? 48 54 66 53 59 -1
How to do it?
New values on next line
Do not cross old values
Blank when no new value
WILL BE ON QUIZ
And Test 1
And Final!

20. Checking Input Range
max = 0; cin >> score; while (score != -1) { if (score >= 0 && score <= 60) if (score > max) max = score; else cout << “Invalid score!”; } // Is it correct? //(ignoring magic nubers) // Which if is else paired with?
max = 0;
cin >> score;
while (score != -1) {
if (score >= 0 && score <= 60)
if (score > max)
max = score;
else
cout << “Invalid score!”; }
//else is paired with the last if!

21. Checking Input Range
const int LOW_LIMIT = 0; const int HIGH_LIMIT = 60; max = LOW_LIMIT; cin >> score; // Prime read while (score != -1) { if (score >= LOW_LIMIT && score <= HIGH_LIMIT) if (score > max) max = score; } else cout << “Invalid score!”; cin >> score;

22. Getting a Valid Value Pseudo Code Input a value
While the input value is out of range
Display a message
Input a new value
cin >> score;
while (score < 0 || score > 60)
cout << “Invalid score!”;
Correct?

23. Getting a Valid Value Pseudo Code Input a value
While the input value is out of range
Display a message
cin >> score;
while (score < 0 || score > 60) {
cout << “Invalid score!”; }
How about the end value -1?

24. Getting a Valid Value Pseudo Code Input a value
While the input value is out of range and not -1
Display a message
cin >> score;
while ((score < 0 || score > 60) && score != -1) {
cout << “Invalid score!”; }
// Is the following correct?
while (score < 0 || score > 60 && score != -1)
// NO! It’s the same as the following:
while (score < 0 || (score > 60 && score != -1))

25. Getting Valid Scores int score, max = LOW_LIMIT;
cout << “Enter a score: ”;
cin >> score;
while (score != END_VALUE && (score < LOW_LIMIT || score > HIGH_LIMIT)) {
cout << “Invalid score: ” << score; }
while (score != END_VALUE)
if (score > max)
max = score;

26. Data Type bool bool badScore;
// Boolean variable with two possible values: true or false
badScore = false; // lower case
cin >> score;
badScore = (score != END_VALUE &&
(score < LOW_LIMIT || score > HIGH_LIMIT));
while (badScore == true) {
cout << “Invalid score: “ << score; }

27. Data Type bool (II) bool badScore; badScore = false;
cin >> score;
badScore = (score != END_VALUE &&
(score < LOW_LIMIT || score > HIGH_LIMIT))
// Change (badScore == true) to badScore
while (badScore) {
cout << “Invalid score: “ << score; }

28. Event-Controlled Loops
Sentinel-Controlled Loops
Boolean-Variable-Controlled Loops
Others

29. Quiz3-1 10 PM Today Lab2 Yesterday (5) Next Tuesday (3) Prog1
Schedule
Quiz PM Today Lab2 Yesterday (5) Next Tuesday (3) Prog1

30. Program 1 Due Tuesday September 22 by 10 pm: 15 points
(two bonus points towards style)
Grace Friday September 25 by 10 pm: 15 points
After Grace Time: 0 points and you still have to do it!
NONE Differences: at least on test 1 (otherwise: F for CS1430)
Do it yourself!

31. Programming Grand Rules
You could lose up to 7 points on style! I can check your Style if you print it out or put it into the DropBox.