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randint() Function in Python
  • Difficulty Level : Basic
  • Last Updated : 23 Oct, 2020

randint() is an inbuilt function of the random module in Python3. The random module gives access to various useful functions and one of them being able to generate random numbers, which is randint().

Syntax :

randint(start, end)

Parameters :

(start, end) : Both of them must be integer type values.

Returns :

A random integer in range [start, end] including the end points.

Errors and Exceptions :

ValueError : Returns a ValueError when floating
             point values are passed as parameters.

TypeError : Returns a TypeError when anything other than 
            numeric values are passed as parameters.

 
Code #1 :






# Python3 program explaining work
# of randint() function
  
# imports random module
import random
  
# Generates a random number between
# a given positive range
r1 = random.randint(0, 10)
print("Random number between 0 and 10 is % s" % (r1))
  
# Generates a random number between 
# two given negative range
r2 = random.randint(-10, -1)
print("Random number between -10 and -1 is % d" % (r2))
  
# Generates a random number between 
# a positive and a negative range
r3 = random.randint(-5, 5)
print("Random number between -5 and 5 is % d" % (r3))

Output :

Random number between 0 and 10 is 5
Random number between -10 and -1 is -7
Random number between -5 and 5 is 2

 
Code #2 : Program demonstrating the ValueError.




# imports random module
import random
  
'''If we pass floating point values as
parameters in the randint() function'''
  
r1 = random.randint(1.23, 9.34)
print(r1)

Output :

Traceback (most recent call last):
  File "/home/f813370b9ea61dd5d55d7dadc8ed5171.py", line 6, in 
    r1=random.randint(1.23, 9.34)
  File "/usr/lib/python3.5/random.py", line 218, in randint
    return self.randrange(a, b+1)
  File "/usr/lib/python3.5/random.py", line 182, in randrange
    raise ValueError("non-integer arg 1 for randrange()")
ValueError: non-integer arg 1 for randrange()

 
Code #3 : Program demonstrating the TypeError.




# imports random
import random
  
'''If we pass string or character literals as
parameters in the randint() function'''
  
r2 = random.randint('a', 'z')
print(r2)

Output :

Traceback (most recent call last):
  File "/home/fb805b21fea0e29c6a65f62b99998953.py", line 5, in 
    r2=random.randint('a', 'z')
  File "/usr/lib/python3.5/random.py", line 218, in randint
    return self.randrange(a, b+1)
TypeError: Can't convert 'int' object to str implicitly

 
Applications :

The randint() function can be used to simulate a lucky draw situation.

Let’s say User has participated in a lucky draw competition. The user gets three chances to guess the number between 1 and 10. If guess is correct user wins, else loses the competition.




# importing randint function
# from random module
from random import randint
  
# Function which generates a new 
# random number everytime it executes
def generator():
    return randint(1, 10)
      
# Function takes user input and returns
# true or false depending whether the
# user wins the lucky draw!
def rand_guess():
  
    # calls generator() which returns a
    # random integer between 1 and 10
    random_number = generator()
      
    # defining the number of
    # guesses the user gets
    guess_left = 3
  
    # Setting a flag variable to check
    # the win-condition for user
    flag = 0
  
    # looping the number of times
    # the user gets chances
    while guess_left > 0:
  
        # Taking a input from the user
        guess = int(input("Pick your number to "
                      "enter the lucky draw\n"))
  
        # checking whether user's guess
        # matches the generated win-condition
        if guess == random_number:
  
            # setting flag as 1 if user guessses 
            # correctly and then loop is broken
            flag = 1
            break
          
        else:
              
            # If user's choice doesn't match
            # win-condition then it is printed
            print("Wrong Guess!!")
  
        # Decrementing number of 
        # guesses left by 1 
        guess_left -= 1
  
    # If win-condition is satisfied then,
    # the function rand_guess returns True
    if flag is 1:
        return True
  
    # Else the function returns False
    else:
        return False
  
# Driver code
if __name__ == '__main__':
    if rand_guess() is True:
        print("Congrats!! You Win.")
    else :
        print("Sorry, You Lost!")

Output :

Pick your number to enter the lucky draw
8
Wrong Guess!!
Pick your number to enter the lucky draw
9
Wrong Guess!!
Pick your number to enter the lucky draw
0
Congrats!! You Win.

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