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Types, Truth, and Expressions

Learn fundamental concepts of Python programming, including types, truth evaluations, and expressions. Get guidance on variable naming, string handling, and if statements. Test your knowledge with interactive exercises. Develop a strong foundation in computer science with Dr. Sarah Diesburg's helpful insights.

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Types, Truth, and Expressions

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  1. Types, Truth, and Expressions Intro to Computer Science CS1510 Dr. Sarah Diesburg

  2. Homework Hints • From now on can use CONSTANT_NAMES for constants • No line wrap

  3. Observations from PA 1 • Variable names matter (don’t call it startingMileageStr when it contains a number) • Why would you import math? • Why would you say float(2.2) • Do your own work!

  4. Questions about PA02??

  5. Line Wrap • Some rules • Strings must be closed in the line in which they start • Adding a backslash at the end of the line tells python that the command is continued on the end of the line

  6. Review : Python if Statement if <expression> : suite • Evaluate the expression to a boolean value (True or False) • if True, execute all statements in the suite

  7. Review : Warning About Indentation • Elements of the “suite” must all be indented the same number of spaces/tabs • Python only recognizes suites when they are indented the same “distance” • You must be careful to get the indentation right to get suites right.

  8. Let’s test your knowledge • Let‘s look at #1-4 in my questions.py program…

  9. Let’s test your knowledge • Problems #1-4 : Which letters are printed? • A • B • A and B • Neither

  10. Let’s test your knowledge • Let’s look at statements with if, elif, else • Problems #5-9 : Which letters are printed? • A • B • A and B • Neither

  11. Python Selection, Round 2 if boolean expression: suite1 else: suite2 The process is: • evaluate the boolean • if True, run suite1 • if False, run suite2

  12. Python Selection, Round 3 if boolean expression1: suite1 elif expression2: suite2 The process is: • evaluate expression1 • if True, run suite1 • If False, evaluate expression 2 • if True, run suite2

  13. Python Selection, Round 3 if boolean expression1: suite1 elif boolean expression2: suite2 #(as many elif’s as you want) else: suiteLast

  14. if, elif, else, the Process • Evaluate boolean expressions until: • The boolean expression returns True • None of the boolean expressions return True • If a boolean returns True, run the corresponding suite. Skip the rest of the if • If no boolean returns True, run the else suite, the default suite

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