Python中的randint()函数

randint()是 Python3 中random 模块的内置函数。 random 模块可以访问各种有用的函数，其中之一能够生成随机数，即randint() 。句法：

randint(start, end)

参数：

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

返回：

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

错误和异常：

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.

代码#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))

输出：

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

代码 #2：演示 ValueError 的程序。

# 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)

输出：

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()

代码 #3：演示 TypeError 的程序。

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

输出：

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

应用：

randint()函数可用于模拟幸运抽奖情况。

假设用户参加了抽奖比赛。用户有 3 次机会猜测 1 到 10 之间的数字。如果猜对了，则用户获胜，否则输掉比赛。

# 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!")

输出：

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.