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Branching statements in Python

  1. Comparison operators
  2. if-else statement

1. Comparison operators

The common comparison operators:
Operator
Meaning
Example
>
greater than
5 > 4 is true
<
less than
4 < 5 is true
>=
greater than or equal
4 >= 4 is true
<=
less than or equal
3 <= 4 is true
==
equal to
1 == 1 is true
!=
not equal to
1 != 2 is true
and
and
a > 4 and a < 10
or
or
a == 1 or a == 4

2. if-else statement

if is a statement which checks a certain condition in Python. For example: If a> b, then do something ....
Syntax:
if condition_1 :
    # Do something

elif condition_2 :
    # Do something

elif condition_N:
    # Do something

else :
    # Do something
The program checks the condition from top to bottom until it encounters a condition that is true, and run this block and the program does not check the remaining conditions in the branching structure.
Example (if - else):
ifElseExample.py
option = 5 

if option == 1:
    print("Hello")
else :
    print("Bye!")
Output:
Bye!
Example (if - elif - else):
ifElseExample2.py
print("Please enter your age: \n")
# Declare a variable to store the user input from the keyboard.
inputStr =  input()

# int(..) function convert string to integer
age = int(inputStr)
# Print out your age
print("Your age: ", age)

# If age < 80 then ..
if (age < 80) :
    print("You are pretty young")
# Else if age between 80, 100 then
elif (age >= 80 and age <= 100) :
    print("You are old")
# Else (Other case)
else :
    print("You are verry old")
Running the example:

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