Python Control Statements

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• if statement
• else clause
• if else-if clause(elif clause)
• match statement

if statements closely associated with , python operators , and their associativitivty and precedence.

Before evaluating any expression, Programmer should be familiar with operators. for ex: age > 18 , > is a relational operator. age > 18 and age < 23 , 'and' is a logical operator. (a+b) == (c+d) , arithmetic operator '+' and equality operator == both used in condition.

Python if Statement

Syntax:

      			if condition:
      			   statements(s)
      		

Example: if statement usage

			# if number is non-zero ,condition is successful, so print statement gets executed.
			num = 1
			if num:
			 print(num)
		

   The above if condition can be rewritten with relational Operators > and <
   if num < 0 or num > 0 : print(num)

   The above if condition can be rewritten with != (not equal to) operator
   if num !=0 : print(num)

Example: if statement usage with Boolean Values

			if True:
			   print('Hello')
			   
			#Prints 'Hello', Gurantee execution of the statement.
		

		        	name=''
		        	if name == '':print('name is empty')
		        	
		        	
		        	#Following Example checks 'name' starts with Capital Letter
		        	name = 'sam'
		        	
		        	if name[0].title().istitle(): name=name[0].title()+name[1:]
		        	print(name)
		        	Sam
		        

Example: if statement usage with in Operator

			address= '123 james street,ma,usa,zip:63663'
			if 'zip' in address:
			   print('Address has ZIP code')
		

Python if Statement with else

Syntax:

      			if condition:
      			   statements(s)
      			else
      			    statement(s)
      		

    condition is true , true block gets executed, condition is False else block gets executed.

Example: Check age for eligibility using simple condition

		      	age = int(input('Enter Your Age:'))
		      	if ( age >= 18 ): print('Eligible for Voting')
		      	else: print('Not Eligible')
		      

Example: Check age for eligibility using compound condition, 'and' logical operator used to check eligibility, age should be between 21 and 35. both conditions must return True. Person should be greater than or equal to 21 and less than or equal to 35.

		      	age = int(input('Enter Your Age:'))
		      	if ( age >= 21 and age <=35 ): print('Eligible for Managereal jobs')
		      	else: print('Not Eligible for Job')
		      

Python if elseif Statement

Syntax:

      			if condition:
      			   statements(s)
      			elif condition:
      			    statement(s)
      			else
      			    statement(s)
      		

Example: Find Maximum of 3 numbers.using if else statement

      			a = 10; b = 20; c = 25
      			
      			max = 'No Max';
      			if a > b and a > c: max = a
      			elif b > c: max = b
      			else:  max = c
			print('maximum number is:',max)
      		

Example: Find High Paid Jobs using if-else-if Statement

Example: Checks Object instance using isinstance function
This example checks whether given object is an instance of tuple ,set or list. isinstance built-in function, returns Trur or False based on object and type, it takes 2 parameters, one is object ,second one is built-in type.
Here x is a Object of type tuple, second param is tuple buil-in type, Similarly for other types.

      			x=1,2,3
      			
      			if isinstance(x,tuple): print('x is a tuple')
      			elif isinstance(x,set): print('x is a set')
      			elif isinstance(x,list): print('x is a list')
      			
      			x is a tuple
      		

Python match statement

Syntax:

      			match condition:
	      			case expr1:
	      			case expr2:
	      			..........
	      			case _:
      		

match is similar to switch-case statement in 'C' Programming

      		match True:
      		    case True: print(True)
      		    case False: print(False)
      		

prints True Example: Find age group using match compound statement

      			age = 24
      			
      			match age :
      			  range(0,19): print('not eligile for job')
      			  range(19,31):print('eligible for job')
      			  range(31,45):print('eligible for managerial job')
      			  range(45,60):print('Senior Manager jobs')
      			  case _: print('Not eligible')