1. CS150 Introduction to Computer Science 1
Announcements
Midterm on Friday, October 17th, 2003
Quiz some time next week
Assignment 3 is due on Wednesday, October 15th, 2003
I am almost done with your grading. I will hand it back to you today during the lab
4/17/2019
CS150 Introduction to Computer Science 1

2. CS150 Introduction to Computer Science 1
Do While Loops do {
cout << “Enter a year:” << endl;
cin >> year;
} while (year < 0);
4/17/2019
CS150 Introduction to Computer Science 1

3. CS150 Introduction to Computer Science 1
When to use do while?
When loop must execute at least once
Perfect for data validation!
Post-tested loop
General format: do {
statements;
} while (condition is true);
4/17/2019
CS150 Introduction to Computer Science 1

4. CS150 Introduction to Computer Science 1
Example
Write a program segment that takes as input a number between 5 and 10. Error proof the segment.
4/17/2019
CS150 Introduction to Computer Science 1

5. CS150 Introduction to Computer Science 1
What’s the output?
m = 10; do {
cout << m << endl;
m = m - 3;
} while (m > 0)
4/17/2019
CS150 Introduction to Computer Science 1

6. CS150 Introduction to Computer Science 1
Rewrite
num = 10;
while (num <= 100) {
cout << num << endl;
num += 10; }
4/17/2019
CS150 Introduction to Computer Science 1

7. CS150 Introduction to Computer Science 1
Rewrite
for (n = 3; n > 0; n--)
cout << n << “ squared is” << n*n << endl;
4/17/2019
CS150 Introduction to Computer Science 1

8. CS150 Introduction to Computer Science 1
Nested Loops
A loop within a loop
Can repeat multiple things within a loop
Example: Read in 10 grades for each of 20 students
4/17/2019
CS150 Introduction to Computer Science 1

9. CS150 Introduction to Computer Science 1
Example
cout << setw(12) << “i” << setw(6) << “j” << endl;
for (int i = 0; i < 4; i++) {
cout << “Outer” << setw(7)<< i;
cout << endl;
for (int j = 0; j < i; j++)
cout << “ Inner” << setw(10);
cout << j << endl; }
4/17/2019
CS150 Introduction to Computer Science 1

10. CS150 Introduction to Computer Science 1
Example
cout << " ";
for (int colhead=0; colhead <10; colhead++)
cout << setw(3) << colhead;
cout << endl;
cout << " " << endl;
for (int row = 0; row < 10; row++) {
cout << setw(3) << row ;
for (int col = 0; col < 10; col++)
cout << setw(3) << row*col; }
4/17/2019
CS150 Introduction to Computer Science 1

11. CS150 Introduction to Computer Science 1
4/17/2019
CS150 Introduction to Computer Science 1

12. CS150 Introduction to Computer Science 1
4/17/2019
CS150 Introduction to Computer Science 1

13. CS150 Introduction to Computer Science 1
What’s the Output
for (int i = 0; i < n; i++) {
for (int j = 0; j < i; j++)
cout << “*”;
cout << endl; }
4/17/2019
CS150 Introduction to Computer Science 1

14. CS150 Introduction to Computer Science 1* **
***
****
4/17/2019
CS150 Introduction to Computer Science 1

15. CS150 Introduction to Computer Science 1
What’s the Output
for (int i = m; i >0; i--) {
for (int j = n; j>0; j--)
cout << “*”;
cout << endl; }
4/17/2019
CS150 Introduction to Computer Science 1

16. CS150 Introduction to Computer Science 1
*****
4/17/2019
CS150 Introduction to Computer Science 1

17. CS150 Introduction to Computer Science 1
Problem
Write a program that outputs a rectangle of stars for any inputted width and height
4/17/2019
CS150 Introduction to Computer Science 1