Python Keywords and Identifiers

10 Jun, 2022
Keywords are some predefined and reserved words in python that have special meanings. Keywords are used to define the syntax of the coding. The keyword cannot be used as an identifier, function, and variable name. All the keywords in python are written in lower case except True and False. There are 33 keywords in Python 3.7 let’s go through all of them one by one.
Identifier is a name used to identify a variable, function, class, module, etc. The identifier is a combination of character digits and underscore. The identifier should start with a character or Underscore then use a digit. The characters are A-Z or a-z, an Underscore ( _ ) , and digit (0-9). we should not use special characters ( #, @, $, %, ! ) in identifiers. 
Examples of valid identifiers:
var1
_var1
_1_var
var_1
Examples of invalid identifiers
!var1
1var
1_var
var#1
Example 1: Example of and, or, not, True, False keywords.
Python
print("example of True, False, and, or not keywords") #  compare two operands using and operatorprint(True and True) # compare two operands using or operatorprint(True or False) # use of not operatorprint(not False)
Output:
example of True, False, and, or not keywords
True
True
True
Example 2: Example of a break, continue.
Python
# execute for loopfor i in range(1, 11):         # print the value of i    print(i)         # check the value of i is less then 5    # if i lessthen 5 then continue loop    if i < 5:         continue             # if i greater then 5 then break loop    else:         break
Output:
1
2
3
4
5
Example 3: example of for, in, if, elif and else keyword.
Python
# run for loopfor t in range(1, 5):  # print one of t ==1    if t == 1:        print('One')   # print two if t ==2    elif t == 2:        print('Two')    else:        print('else block execute')
Output:
One
Two
else block execute
else block execute
Example 4: Example of def, if, and else keywords.
Python
# define GFG() function using def keyworddef GFG():    i=20    # check i is odd or not    # using if and else keyword    if(i % 2 == 0):        print("given number is even")    else:        print("given number is odd")        # call GFG() function   GFG()
Output:
given number is even
Example 5: example try, except, raise.
Python
def fun(num):    try:        r = 1.0/num    except:        print('Exception raises')        return    return r print(fun(10))print(fun(0))
Output:
0.1
Exception raises
None
Example 6: Example of a lambda keyword.
Python
# define a anonymous using lambda keyword# this lambda function increment the value of ba = lambda b: b+1 # run a for loopfor i in range(1, 6):    print(a(i))
Output:
2
3
4
5
6
Example 7: use of return keyword.
Python
# define a functiondef fun():  # declare a variable    a = 5    # return the value of a    return a# call fun method and store# it's return value in a variable t = fun()# print the value of tprint(t)
Output:
5
Example 8: use of a del keyword.
Python
# create a listl = ['a', 'b', 'c', 'd', 'e'] # print list before using del keywordprint(l) del l[2] # print list after using del keywordprint(l)
Output:
['a', 'b', 'c', 'd', 'e']
['a', 'b', 'd', 'e']
Example 9: use of global keyword.
Python
# declare a variablegvar = 10 # create a functiondef fun1():  # print the value of gvar    print(gvar) # declare fun2()def fun2():  # declare global value gvar    global gvar    gvar = 100 # call fun1()fun1() # call fun2()fun2()
Output:
10
Example 10: example of yield keyword.
Python
def Generator():    for i in range(6):        yield i+1 t = Generator()for i in t:    print(i)
Output:
1
2
3
4
5
6
Example 11: Use of assert keyword.
Python3
def sumOfMoney(money):    assert len(money) != 0,"List is empty."    return sum(money) money = []print("sum of money:",sumOfMoney(money))
Output:
AssertionError: List is empty.
Example 12: Use of pass keyword
Python3
class GFG:    passg = GFG
 
Example 13: Use of finally keyword 
Python3
def divide(a, b):    try:        c = a/b        print("Inside try block")    except:        print("Inside Exception block")    finally:        print("Inside finally block")divide(3,2)divide(3,0)
Inside try block
Inside finally block
Inside Exception block
Inside finally block
Example 14: Use of import keyword
Python3
import mathprint("factorial of 5 is :", math.factorial(5))
factorial of 5 is : 120
Example 15: Use of is keyword 
Python3
x = 10y = 20z = xprint(x is z)print(x is y)
True
False
Example 16: Use of from keyword 
Python3
from math import gcdprint("gcd of 345 and 675 is : ", gcd(345, 675))
gcd of 345 and 675 is :  15
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