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cs2370 Notes: 01 Welcome

··2 mins

Intro to programming first day

Hello #

  • Hello
  • Programming
    • Computers are pretty useful
    • Computers run code that transforms data
    • Let’s figure out this code and data stuff
  • Attendence

Syllabus #

  • Attendence is strongly recommended.
    • Also, eating and sleeping.
  • The lecture and lab are one course.
  • Lab assignments are the largest grade component. You’ll work in pairs and write code.
  • The final exams are on paper, and really will include writing code with a pencil.
  • We’ll see an autograding example in lab tomorrow.
  • There will be tutoring at some point.
  • Please don’t cheat.

Introducing Python Code #

print("One")
print("Two")
print("Three")
  • Write the code in IDLE
  • We need to save it before we can run it.
  • That means we care about local files and directories.
  • This is a plain text file.
    • We can open it in Windows Notepad
    • A program like Microsoft Word won’t work.
  • We can run it by:
    • Clicking “run” in the run menu.
    • Pressing F5.
    • Opening up a command line window and running it with the python command.
  • A Python program is a series of statements (think “commands”)
  • The Python interpreter (a program called “python”) executes the program in such a way that it looks like the statements run in order.
  • The print function prints something out.
print("Input x")
text = input("> ")
x = int(text)
print("x + 4 =", x + 4)

This example has a several new compliications:

  • The “input” function reads a line of text from the user.
  • Execution of the program stops until the user finishes typing and presses enter.
  • We can store things in variables, giving them a name so we can refer to them later.
  • We have two different types of value: strings and integers.
  • Functions sometimes accept more than one argument, seperated by commas.

Interactive examples:

>>> 3 + 2
>>> a = 3
>>> a + 2

>>> "3" + 2
>>> int("3")
>>> '3'
>>> str(3)
>>> 2 + int("3")
>>> "2" + str(3)

>>> print("hi")
>>> print("a", "b")
>>> print("a", 3, "b")
>>> type('hi')
>>> type(3)
>>> type(3 / 2)