Python OverView

1.1 Python Overview

Python is formally an interpreted language. Commands are executed through the Python interpreter. Programmer usually uses the source code or script to save his command.

print( Welcome to the GPA calculator. )
print( Please enter all your letter grades, one per line. ) print( Enter a blank line to designate the end. )
# map from letter grade to point value
points = { A+ :4.0, A :4.0, A- :3.67, B+ :3.33, B :3.0, B- :2.67,
C+ :2.33, C :2.0, C :1.67, D+ :1.33, D :1.0, F :0.0}
num courses = 0
total points = 0
done = False
while not done:
   grade = input( )   # read line from user
   if grade == :   # empty line was entered
      done = True
   elif grade not in points:   # unrecognized grade entered
      print("Unknown grade {0} being ignored".format(grade))
      else:
   num courses += 1
total points += points[grade]
if num courses > 0: # avoid division by zero
print( Your GPA is {0:.3} .format(total points / num courses))

1.2 Objects in Python

Assignment statement

temperature = 98.6

It makes this temperature as an identifier and then associates it with the object expressed on the right-hand side of the equal sine.

Because Python is a dynamically typed language it associates an identifier with any type of object.

Instantiation

The process of creating a new instance of a class is known as instantiation. If there were a class named Widget, we could create an instance of that class using a syntax such as w=Widget()