We use a comparison operator to compare values. It will return a boolean value
A comparison operator can be used to compare data of the same types
# Value for all comparison operators listed below is True
10 > 3 # Greater than
10 >=3 # Greater than or equal to
10 < 20 # Less than
10 <= 20 # Less than or equal to
10 == 10 # Equal to
10 != "10" # Not equal to
"bag" > "apple" # When we sort these two strings bag comes after apple thats why true
print(ord("b")) # is 98
print(ord("B")) # is 66
Conditional Statements
If statement will contain an expression that will return a boolean(True, False) value
If we use an if statement, always terminate it with a colon
All the statement which are indented by a tab will belong to this if statement
# Self explanatory conditional statement example is here
temperature = 35
if temperature > 30:
print("Inside if")
print("Still inside if")
elif temperature > 20:
print("Inside elif")
else:
print("This is optional")
print("Outside if")
Ternary Operator
Using ternary operator we can write multiple conditions in one line itself
# Sample if condition
age = 22
if age >= 18:
message = "Eligible"
else:
message = "Not Eligible"
print(message)
# Same if condition using Ternary Operator
age = 22
message = "Eligible" if age >= 18 else "Not Eligible"
print(message)
Logical Operator
We have three types of logical operators: "and", "or", and "not"
"and" operator
# If both the conditions are true the result will be true
high_income = False
good_credit = True
if high_income and good_credit:
print("Eligible")
else:
print("Not eligible")
"or" operator
# If one of the many conditions are true the result will be true
high_income = False
good_credit = True
if high_income or good_credit:
print("Eligible")
else:
print("Not eligible")
"not" operator
# It inverses the value of a boolean
student = True
if not student:
print("Eligible")
else:
print("Not eligible")
Short Circuit Evaluation
In python the if statement is evaluated from left to right
In case of "and" if any argument is false then it stops the evaluation of further arguments
In case of "or" if any argument is true then it stops the evaluation of further arguments
In python, logical operators are short circuit
high_income = False
good_credit = True
student = True
# checked for high_income, it's False, so does not evaluate any further
if high_income and good_credit and not student:
print("Eligible")
else:
print("Not eligible")
Chaining Condition Operator
age = 22
# Noraml if condition
if age >= 18 and age <65:
print("Eligible")
# If condition using chaining
if 18 <= age < 65: # "18 <= age < 65" is called chaining comparison operator
print("Eligible")
Loops
"range"
range(4)
#It will return a sequence from 0 to 3
range(1,4)
#It will return a sequence from 1 to 3
range(0,4,2)
#It will return a sequence from 0 to 3 incremented by step of 2
"for" Loop
We use loops to create repetition
Similar to if statements we need to terminate our for loop with colon(:)
for number in range(1,4):
print("Attempt",(number), (number) * "." )
Break Statement
count = 0
for number in range(25):
print(number)
if count == 10:
break
Nested Loop
for loop within for loop
for x in range(5):
for y in range(3):
print("Coordinates", x, y)
Iterables
Iterable is an object, which one can iterate over.
Previously we saw range() function, which returns an object which is iterable.
# range as iteranle
for number in range(3):
print(number)
# string as iterable
for character in "String":
print(character )
# list as iterable (note that we can have different dtypes in lists)
for list_item in [1,"string",4,7]:
print(list_item )
"while" Loop
number = 100
while number > 0:
print(number)
number = number/2
Infinite Loop
It a loop that runs forever We can break an infinite loop using a break statement
# the code will keep on taking input and printing, unless quit is the input
while True:
command = input(">")
print("Echo",command)
if command.lower() == "quit":
break