3.1.6.1. Syntax of Assignment Sentences¶

• Single equals = is used for assignment to variables

• Double equals == is used for testing equality

• Plus equals += is used to add to an existing variable (can also be used with all other operators)

3.1.6.2. Semantics of Assignment Sentences¶

Setting two variables equal to each other copies the value stored in one and assigns it to the other. However, if one of the variables is changed later, the other one will not change e.g.

# Assignment
# =
# +=
# -=
# /=
# *=
# **=

a=2
b=3
print "example 1:",a,b
a=b
print "example 2:", a,b
b=4
print "example 3:",a,b

example 1: 2 3
example 2: 3 3
example 3: 3 4

my_age = 51
print my_age

51

#birthday  - add one
my_age = 51 + 1
print my_age

#better
my_age = my_age + 1
print my_age

#better still
my_age += 1
print my_age

52
53
54