*Memo:
- My post explains the unpacking with an assignment statement (1).
- My post explains a global statement and nonlocal statement.
- My post explains an identifier.
- My post explains naming convention.
- My post explains a function (1).
A value can be assigned to a variable as shown below:
v = 5
print(v)
# 5
v = 10
print(v)
# 10
A value can be assigned to one or more variables at once as shown below:
# Equivalent
v1 = v2 = v3 = 5 # v1 = 5
# v2 = v1
# v3 = v2
print(v1, v2, v3) # 5, 5, 5
v2 = 10
print(v1, v2, v3)
# 5, 10, 5
The calculation code can be shortened as shown below:
v = 7
# Equivalent
v += 9 # v = v + 9
print(v)
# 16
# Equivalent
v -= 2 # v = v - 2
print(v)
# 14
# Equivalent
v *= 10 # v = v * 10
print(v)
# 140
# Equivalent
v /= 3 # v = v / 3
print(v)
# 46.666666666666664
# Equivalent
v //= 6 # v = v // 6
print(v)
# 7.0
# Equivalent
v %= 4 # v = v % 4
print(v)
# 3.0
A del statement can be used to remove one or more variables themselves as shown below:
v1 = 'Hello'
v2 = 'World'
print(v1, v2)
# Hello World
del v1, v2
print(v1)
# NameError: name 'v1' is not defined
print(v2)
# NameError: name 'v2' is not defined
The name of a variable:
- can have letters,
_
and the digits except for the 1st character. - can be a reserved soft keyword.
- cannot start with a digit.
- cannot be a reserved keyword.
True_100 = 'abc'
tRuE_100 = 'abc'
_True100 = 'abc'
True100_ = 'abc'
match = 'abc'
case = 'abc'
type = 'abc'
_ = 'abc'
# No error
True-100 = 'abc'
100_True = 'abc'
True = 'abc'
class = 'abc'
def = 'abc'
# Error
The naming convention for a variable and constant is lower_snake_case and UPPER_SNAKE_CASE respectively as shown below:
var = 'abc'
my_var = 'abc'
my_first_var = 'abc'
PI = 3.141592653589793
E = 2.718281828459045
MIN_NUM = 0
MAX_NUM = 100
MY_MIN_NUM = 0
MY_MAX_NUM = 100
The variable with a single trailing underscore(abc_
) can be used to prevent identifier conflicts when using the identifiers which already exist as shown below:
var_ = 'ok'
VAR_ = 'ok'
func_ = 'ok'
len_ = 'ok'
list_ = 'ok'
int_ = 'ok'
True_ = 'ok'
def_ = 'ok'
class_ = 'ok'
Top comments (0)