Tuesday, 30-Aug

• • Chapter 3 Quiz now has 3 attempts possible.

    • Deadline extended until 31-August 10:00 pm

  • Rick added the new page Python Resources (link to the left)

    • It includes links for installing Python 3.2 on Mac and Windows machine.

    • It also has links to Python tutorials and documentation.

    • Note: John Zelle's Appendix A, pages 469..477 provides a concise reference.

  • Programming Project 1 Linked. Due next Tuesday, 6-Sep, at 4:00 pm

Homework

• • Work on Project 1: Three programs (in files lightning.py, energy.py, and population.py)

Lecture Outline

1) Consider Project 1 (see Projects page)

• • Recommended: Read the grading criteria (it's not often you're told in advance how you work is graded)

  • You may put all code in def main(): like the book, but you don't need to

    • If you do, indent all code you want to execute. 4 spaces is typical

    • And at the bottom, add main() that calls your main() function

2) Chapter 3: Computing with Numbers

• • There are two types of numbers int as in 12345 or -5 and double as in 4.5 and -1.2e+3

  • float has limited precision

  • int doesn't have overflow, cool

  • Use / for regular division 5.0/2.0 is 2.5, so is 5/2 even though both operands are int

• When operands are mixed, promote int to float

  • for example, (6 + 9.9) becomes 6.0 + 9.9 = 15.9

  • Integer arithmetic is sometimes useful. Use // to get an int

    • 13 // 5 is 2 (the quotient)

    • 13 % 5 is 3 (the remainder)

  • int('123') is the integer 123

  • float('123') is the floating point number 123.0

• float('not a number') and int('x') are ValueErrors

3) Code demo: Compute the minimum number of coins to return for any given change from 0 to 99 cents:

The local supermarket has asked you to develop a program to return change to their customers with

the caveat that you always compute the minimum number of coins. This supermarket doesn't want to

give a customer 99 pennies for change of 99 cents. Rather, they prefer to return 3 quarters, 2 dimes,

and 4 pennies (the only coins to return for change are quarters, dimes, nickels , and pennies).

To begin, write a Python program that reads the amount of change assumed to be in the range

of 0..99 and prints the number of quarters, dimes, nickels, and pennies. Here is a sample dialog:

Enter change: 41

Quarter: 1

Dimes: 1

Nickels: 1

Pennies: 1

4) In class activity (see handout)