Python – Keywords

Python keywords are the reserved words for python programming language. These keywords cannot be used for any other purpose than they have been designed for.

There are 35 keywords in Python – listed below with their uses.

KeywordDescription
andA logical AND operator. Return True if both statements are True.

			x = (5 > 3 and 5 < 10)
			print(x)	# True
			
orA logical OR operator. Returns True if either of two statements is true. If both statements are false, the returns False.

			x = (5 > 3 or 5 > 10)
			print(x)	# True
			
asIt is used to create an alias.

			import calendar as c
			print(c.month_name[1])	#January
			
assertIt can be used for debugging the code. It tests a condition and returns True , if not, the program will raise an AssertionError.

		x = "hello"

		assert x == "goodbye", "x should be 'hello'"  # AssertionError
		
asyncIt is used to declare a function as a coroutine, much like what the @asyncio.coroutine decorator does.

async def ping_server(ip):
awaitIt is used to call async coroutine.

		async def ping_local():
    		return await ping_server('192.168.1.1')
		
classIt is used to create a class.

		class User:
		  name = "John"
		  age = 36
		
defIt is used to create or define a function.

		def my_function():
		  print("Hello world !!")

		my_function()
		
delIt is used to delete objects. In Python everything is an object, so the del keyword can also be used to delete variables, lists, or parts of a list, etc.

		x = "hello"

		del x
		
ifIt is used to create conditional statements that allows us to execute a block of code only if a condition is True.

		x = 5

		if x > 3:
		  print("it is true")
		
elifIt is used in conditional statements and is short for else if.

		i = 5

		if i > 0:
	        print("Positive")
	    elif i == 0:
	        print("ZERO")
	    else:
	        print("Negative")
		
elseIt decides what to do if the condition is False in if..else statement.

		i = 5

		if i > 0:
	        print("Positive")
	    else:
	        print("Negative")
		

It can also be use in try...except blocks.

		x = 5

		try:
		    x > 10
		except:
		    print("Something went wrong")
		else:
		    print("Normally execute the code")
		
tryIt defines a block of code ot test if it contains any errors.
exceptIt defines a block of code to run if the try block raises an error.

		try:
		    x > 3
		except:
		    print("Something went wrong")
		
finallyIt defines a code block which will be executed no matter if the try block raises an error or not.

		try:
		    x > 3
		except:
		    print("Something went wrong")
		finally:
			 print("I will always get executed")
		
raiseIt is used to raise an exception, manually.

		x = "hello"

		if not type(x) is int:
		  	raise TypeError("Only integers are allowed")
		
FalseIt is a Boolean value and same as 0.
TrueIt is a Boolean value and same as 1.
forIt is used to create a for loop. A for loop can be used to iterate through a sequence, like a list, tuple, etc.

		for x in range(1, 9):
  			print(x)
		
whileIt is used to create a while loop. The loop continues until the conditional statement is false.

		x = 0

		while x < 9:
		  	print(x)
		  	x = x + 1
		
breakIt is used to break out a for loop, or a while loop.

		i = 1 

		while i < 9:
		  	print(i)
		  	if i == 3:
		    	break
		  	i += 1
		
continueIt is used to end the current iteration in a for loop (or a while loop), and continues to the next iteration.

		for i in range(9):
		  	if i == 3:
		    	continue
		  	print(i)
		
importIt is used to import modules.

import datetime
fromIt is used to import only a specified section from a module.

from datetime import time
globalIt is used to create global variables from a no-global scope, e.g. inside a function.

		def myfunction():
		  	global x
		  	x = "hello"
		
in1. It is used to check if a value is present in a sequence (list, range, string etc.).
2. It is also used to iterate through a sequence in a for loop.

		fruits = ["apple", "banana", "cherry"]

		if "banana" in fruits:
		  	print("yes")

		for x in fruits:
  			print(x)
		
isIt is used to test if two variables refer to the same object.

		a = ["apple", "banana", "cherry"]
		b = ["apple", "banana", "cherry"]
		c = a

		print(a is b)	# False
		print(a is c)	# True
		
lambdaIt is used to create small anonymous functions. They can take any number of arguments, but can only have one expression.

		x = lambda a, b, c : a + b + c

		print(x(5, 6, 2))
		
NoneIt is used to define a null value, or no value at all. None is not the same as 0, False, or an empty string.
None is a datatype of its own (NoneType) and only None can be None.

		x = None

		if x:
		  print("Do you think None is True")
		else:
		  print("None is not True...")		# Prints this statement

		
nonlocalIt is used to declare that a variable is not local. It is used to work with variables inside nested functions, where the variable should not belong to the inner function.

		def myfunc1():
		  	x = "John"
		  	def myfunc2():
		    	nonlocal x
		    	x = "hello"
		  	myfunc2()
		  	return x

		print(myfunc1())
		
notIt is a logical operator and reverses the value of True or False.

		x = False

		print(not x)	# True
		
passIt is used as a placeholder for future code. When the pass statement is executed, nothing happens, but you avoid getting an error when an empty code is not allowed.

Empty code is not allowed in loops, function definitions, class definitions, or in if statements.

for x in [0, 1, 2]:
  			pass
returnIt is to exit a function and return a value.

def myfunction():
  			return 3+3
withUsed to simplify exception handling
yieldTo end a function, returns a generator

Happy Learning !!

Ref : W3 Schools

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