Python Boolean Operators
April 02, 2019
or, and, not. The or and and are short-circuit operators. The highest priority of Boolean operators is not then and and then or operator. The not operator has the lower priority than non-Boolean operators.
Boolean operators are evaluated as following.
| Operation | Result |
|---|---|
| x or y | if x is false, then y, else x |
| x and y | if x is false, then x, else y |
| not x | if x is false, then True, else False |
For the demo we are using Python 3.7.0 in our example. Now find the Python Boolean operators in detail.
1. or Operator
or operator works as following.
| Operation | Result |
|---|---|
| True or True | True |
| True or False | True |
| False or True | True |
| False or False | False |
or operator is a short-circuit operator, so it only evaluates the second argument if the first one is False.
Now find the examples of
or operator.Ex1.
a = 40
if a > 100 or a < 50 :
print ('Valid number')
else :
print ('Invalid number')
Valid number
name = "Mahesh"
if name.startswith("S") or name.startswith("M") :
print ('Valid name')
else :
print ('Invalid name')
Valid name
2. and Operator
and operator works as following.
| Operation | Result |
|---|---|
| True and True | True |
| True and False | False |
| False and True | False |
| False and False | False |
and operator is a short-circuit operator, so it only evaluates the second argument if the first one is True.
Now find the examples of
and operator. Ex1.
a = 30
if a > 10 and a < 50 :
print ('Valid number')
else :
print ('Invalid number')
Valid number
name = "Suresh"
if name.startswith("S") and name.endswith("h") :
print ('Valid name')
else :
print ('Invalid name')
Valid name
3. not Operator
not operator works as following.
| Operation | Result |
|---|---|
| not True | False |
| not False | True |
Now find the examples of
not operator.Ex1.
name = "Krishna"
if not name.startswith("S") :
print ('Valid name')
else :
print ('Invalid name')
Valid name
name = "Krishna"
if not name.endswith("a") :
print ('Valid name')
else :
print ('Invalid name')
Invalid name
Priorities of Boolean Operators
The highest priority of Boolean operators isnot then and and then or operator. The not operator has the lower priority than non-Boolean operators.
1.
and has the higher priority than or operator.
>>> True and False or True True
>>> (True and False) or True True
x= 10
if x > 5 and x < 10 or x%2==0 :
print ('Valid number')
else :
print ('Invalid number')
Valid number
if statement is same as following.
if (x > 5 and x < 10) or x%2==0 :
not has the higher priority than and operator.
>>> not False and True True
>>> (not False) and True True
name = "Mahesh"
if not name.startswith("S") and name.endswith("h") :
print ('Valid name')
else :
print ('Invalid name')
Valid name
if statement is same as following.
if (not name.startswith("S")) and name.endswith("h") :
not operator has the lower priority than non-Boolean operators.
>>> not True == True False
>>> not (True == True) False
name = "Mahesh"
if not name.index("a") == 1 :
print ('Valid name')
else :
print ('Invalid name')
Invalid name
if statement is same as following.
if not (name.index("a") == 1) :
References
Boolean Operations - and, or, notPython Getting Started
