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Like all programming languages, Python gives us a conditional if statement, which is used when we want to test a condition. This condition is evaluated for a boolean value - true or false.

• If this condition is true then the statement or a block of statements connected to the If statement is executed.


• If this continue is false then the statement or a block of statements connected to the If statement is not executed.

Note: Instead of a condition, there could even be a variable which returns a non-zero value or just a non-zero value.

Important points - if statement

• As you can see in the diagram above, in Python, an if statement needs a colon: right after declaring its condition, which helps us in declaring the start of an upcoming indented block and it also improves readability.


• In Python, the condition of an if statement can be declared without a pair of parentheses () around it(contrary to many programming languages like C, C++ which require us to wrap a condition within a pair of parentheses).


• Unlike many programming languages like C, C++, Java which require a pair of braces { } to hold multiple statements associated with an if statement, Python language does not require you to use a pair of braces { } to contain one or more statements with an if statement.


• Using a pair of braces { } to hold one or more statements with an if statement gives an error.


• Then how do we associate one or multiple statements with an if statement?
  In Python, indentation is meaningful and using it we can associate one or more statements with an if statement.





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Python - if statement example




#Python - if conditional statement program
  

#First if statement
if(10>5):
	print ("10 is greater than 5")


#Second if statement
if(50<100):
	print("50 is less than 100")
	print("Second statement associated with if statement")
	
	
#Third if statement
if(2>4):
	print("2 is greater than 4")
print("Statement outside if Statement") #This line is not associated with any if block





Output is -




10 is greater than 5
50 is less than 100
Second statement associated with if statement
Statement outside if Statement






Program Analysis

• The first if statement condition - 1 0>5, is true, hence its associated print statement is executed.
• The second if statement condition - 50>100 is true, hence its associated two print statements are executed.
• The third if statement condition - 2>4 is false, hence its associated print statement is not executed.
• Finally, the print statement outside the third if block is executed without an issue because it is not associated with the third if statement, due to the absence of its indentation with the third if statement.






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