Outline for April 3, 2014

1. Python, files and shells
   1. Python: programming language that you use to tell the computer what to do
   2. Shell: what you can type Python statements directly into, to see what they do
   3. IDLE: the program that interprets Python statements (executes the Python program)
   4. File: type Python statements into this, and then have IDLE execute those statements by running the program in the file
2. First program: hello, world [hello0.py]
   1. Explain printing
   2. Demonstrate program in IDLE
3. Variables
   1. What they are
   2. Variable names
   3. Variable types (int, float, string)
   4. Python keywords
4. Statements
5. Simple assignment: variable = expression
6. Expressions
   1. Operators +, -, *, /, //, %, **
   2. Precedence
      1. Parentheses for grouping ((, ))
      2. Exponentiation (**); associates right to left
      3. Positive, negative (unary +, -)
      4. Multiplication, division, integer division, remainder (*, /, //, %)
      5. Addition, subtraction (binary +, -)
      6. In general, operators of equal precedence are evaluated from the left to the right (associativity); exception noted above
7. Examples
   1. Temperature conversion [temp.py]
   2. Compute the hypotenuse of a right triangle [hypotnoex.py]
8. The difference between strings and integers [twoplustwo.py]
   1. Difference between ’2 + 2’, 2 + 2
   2. Print statements usually end lines
   3. Getting print statements not to end lines