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11.1.1.8 use logical operations AND, OR, NOT in selection structure
Python. Logic operations AND, OR, NOT
Boolean logic. Truth tables.
| Operator |
Description |
Example |
| and |
Returns True if both statements are true |
x >= 5 and x < 10 |
| or |
Returns True if one of the statements is true |
x < 5 or x > 15 |
| not |
Reverse the result, returns False if the result is true |
not(x >= 5 and x < 10) |
Priority of logic operations:
High to low:
1. not
2. and
3. or
Question. Define the sequence of logic operators:
A and B or not C
- Answer.
1. Q1 = not C
2. Q2 = A and B
3. Q = Q1 or Q2
Example 1
username = input("Username: ")
password = input("Password: ")
if username == "root" and password == "123456":
print("User logged in.")
else:
print("Incorrect username or password.")
Example 2
email = input("Username: ")
phone = input("Phone: ")
if email == "ex@gmail.com" or phone == "+77771234567":
password = input("Password:")
if password == "123456":
print("User logged in.")
else:
print("Incorrect password.")
else:
print("Incorrect email or phone.")
Example 3
email = input("Username:")
phone = input("Phone")
if not(email == "ex@gmail.com" or phone == "+77771234567"):
print("Incorrect email or phone number.")
else:
password = input("Password:")
if password == "123456":
print("User logged in.")
else:
print("Incorrect password.")
Questions:
1. Name logic operations.
2. In which case we can use each logic operation.
Exercises:
Ex. 1. Define the sequence of actions in logic expression.
Ex. 2. Give result of logic operations (True/False)
Tasks:
Tasks on Stepik.org course "Python Programming for NIS" |