Operator
- Arithmetic
python
print(3//2) # 1 整除取商
print(-3//2) # -2*2 + 1 = -3- Logical
python
print(True and True)
print(False or True)
print(not True)- Type Affect Semantics
python
3*"abc" # abcabcabc
3+"abc" # throw error- operator order
python
# ** associates right-to-left
print(4**3**2) # prints 262144, not 4096- approximate values of floating-point numbers
python
print(0.1 + 0.1 == 0.2) # True, but...
print(0.1 + 0.1 + 0.1 == 0.3) # False!
from math import isclose
isclose(0.3,0.1+0.1+0.1,rel_tol=10**-10) # True!
def almostEqual(d1, d2):
return abs(d1 - d1) < 0.1- check type
python
type(x,<Type String>)
isinstance(x, <Type Object>) # more robust
def isString(input):
# return type(input) == str
return isinstance(str)
def isNumber(input):
import numbers
return isinstance(numbers.Number)