Conditional statement in python language

There comes situations in actually when we want to make some decisions and based on these decisions, we decide what would it be a good idea for us we do next. Comparable situations arise in programming likewise where we need to make some decisions and based on these decisions we will execute the next block of code. Decision-making proclamations in programming languages decide the direction of the flow of program execution. 

In Python, if else elif statement is utilized for decision making.

if statement in python

if statement is the most straightforward decision-making statement. It is utilized to conclude whether a specific statement or block of statements will be executed or not i.e if a certain condition is true then a block of statement is executed in any case not.

Syntax: 

if condition:
# Statements to execute if
# condition is true

Here, the condition after assessment will be either true or false. if statement accepts boolean values – assuming the value is true then it will execute the block of statements beneath it in any case not. We can utilize condition with bracket ‘(‘ ‘)’ also. 

As we know, python uses space to identify a block. So the block under an if statement will be identified as displayed in the underneath example:  

if condition:
statement1
statement2
# Here if the condition is true, if block
# will consider only statement1 to be inside
# its block.

Example: if Statement in Python

"""python program to illustrate 
   If statement"""

i = 10

if (i > 15):
	print("10 is less than 15")
print("I am Not in if")

Output:

I am Not in if

As the condition present in the if statement is false. In this way, the block underneath the if statement is not executed.

if-else statement in python

The if statement alone let's us that assuming a condition is true it will execute a block of statemenwets and assuming the condition is false it will not. Be that as it may, imagine a scenario where  want to do something else if the condition is false. Here comes the else statement. We can utilize the else statement with if statement to execute a block of code when the condition is false. 

Syntax:

if (condition):
# Executes this block if
# condition is true
else:
# Executes this block if
# condition is false

Example 1: Python if else statement

"""python program to illustrate 
If else statement"""
#!/usr/bin/python

i = 20
if (i <15):
	print("i is smaller than 15")
	print("i'm in if Block")
else:
	print("i is greater than 15")
	print("i'm in else Block")
print("i'm not in if and 
        not in else Block")

Output:

i is greater than 15
i'm in else Block
i'm not in if and not in else Block

The block of code accompanying the else statement is executed as the condition present in the if statement is false after calling the statement which isn't in block(without spaces).

Example 2: Python if else in list comprehension

# Explicit function
def digitSum(n):
	dsum = 0
	for ele in str(n):
		dsum += int(ele)
	return dsum


# Initializing list
List=[367,111,562,945,6726,873]

"""Using the function on odd 
   elements of the list"""
newList=[digitSum(i) for i in List 
           if i & 1]

# Displaying new list
print(newList)

Output:-

[16, 3, 18, 18]

nested-if statement in python

A nested if is an if statement that is the objective of another if statement. Nested if statements mean an if statement inside another if statement. Yes, Python permits us to nest if statements inside if statements. i.e, we can put an if statement inside another if statement.

Syntax:

if (condition1):
# Executes when condition1 is true
if (condition2):
# Executes when condition2 is true
# if Block is end here
# if Block is end here

Example:

"""python program to illustrate 
    nested If statement"""
#!/usr/bin/python
i = 10
if (i == 10):

   # First if statement
   if (i < 15):
	 print("i is smaller than 15")
		
   # Nested - if statement
   """Will only be executed 
        if statement above"""
   # it is true
   if (i < 12):
	 print("i is smaller than 12 too")
   else:
	 print("i is greater than 15")

Output:

i is smaller than 15
i is smaller than 12 too

if-elif-else ladder

Here, a user can choose different options. The if statements are executed starting from the top . When one of the conditions controlling the if is true, the statement related with that if is executed, and the rest of the stepping stool is bypassed. If none of the conditions is true, then the final else statement will be executed.

Syntax:

if (condition):
statement
elif (condition):
statement
.
.
else:
statement

Example:  if else elif statements

"""Python program to illustrate 
  if-elif-else ladder"""
#!/usr/bin/python

i = 20
if (i == 10):
	print("i is 10")
elif (i == 15):
	print("i is 15")
elif (i == 20):
	print("i is 20")
else:
	print("i is not present")

Output:

i is 20

Short Hand if statement in python

Whenever there is only a single statement to be executed within the if block then shorthand if can be utilized. The statement can be place on the same line as the if statement. 

Syntax:

if condition: statement

Example:

"""Python program to illustrate 
   short hand if"""
i = 10
if i < 15:
	print("i is less than 15")

Output:

i is less than 15

Short Hand if-else statement in python

This can be utilized to write the if-else statements in a single line where there is only one statement to be executed in both if and else block. 

Syntax:

statement_when_True if condition else statement_when_False

Example:

""" Python program to illustrate 
  short hand if-else"""
i = 10
print(True) if i<15 else print(False)

Output: 

True

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