比较两个变量python 3时收到类型错误答案

【问题标题】：Receiving type error when comparing two variables python 3比较两个变量python 3时收到类型错误
【发布时间】：2020-07-22 22:59:00
【问题描述】：

Python 3 代码

import time

list = [1,2,3,4,2323449,1,525]

def Search(arr):
    # sorting
    i = 0
    print(f"Given list: {list}")
    print("Sorting...")
    time.sleep(1.75)
    for i in range(len(list)): 
        if i + 1 >= len(list):
            break
        elif  list[i + 1] < list[i]: 
            list.sort()
            print("List has been sorted ")
            print(f"Sorted list: {list}")
    #---------------------------------------
    # searching
    inputCheck = True
    while inputCheck:
        n = input("Enter a number to find in the list: ")
        try:
            int(n)
            inputCheck = False                                                                                                                                                                                            
        except ValueError or TypeError:
            print("Please enter a number")
            time.sleep(0.6)



    print("Searching...")

    l = 0
    h = len(list) - 1 

    while l <= h:
        mid = (l + h) // 2

        if list[mid] == n:
            pos = mid
            print(f"Found at index {pos}")
            break
        else:
            print(n)
            if list[mid] < n:
                l = mid
            else:
                h = mid
            
Search(list)

我正在尝试制作一个二进制搜索程序，用户在其中输入需要在列表中找到的数字，但是当执行此代码时，我收到此错误：

if list[mid] < n:
TypeError: '<' not supported between instances of 'int' and 'str'

任何帮助将不胜感激！！！

【问题讨论】：

input("Enter...) 给你一个字符串。稍后你将它与一个数字进行比较。您可以将输入行转换为 int：n = int(input("Enter a number to find in the list: "))
或者在您的“try”块中...您需要通过执行以下操作来捕获 n 到 int 的转换：n = int(n)

标签： python-3.x type-conversion

【解决方案1】：

您的实现中存在一些错误

如果输入是有效数字，则搜索块将执行，因此，在 try 块中，您必须存储 n 的值，即 n=int(n)。
如果列表中不存在n，则l=mid 和h=mid 将无限运行while 循环，因为您已经检查了索引mid，因此在while 循环中设置l=mid+1 和h=mid-1的二分查找。

请在需要更改的地方查看下面的 cmets 代码

import time

list = [1,2,3,4,2323449,1,525]

def Search(arr):
    # sorting
    i = 0
    print(f"Given list: {list}")
    print("Sorting...")
    time.sleep(1.75)
    for i in range(len(list)): 
        if i + 1 >= len(list):
            break
        elif  list[i + 1] < list[i]: 
            list.sort()
            print("List has been sorted ")
            print(f"Sorted list: {list}")
    #---------------------------------------
    # searching
    inputCheck = True
    while inputCheck:
        n = input("Enter a number to find in the list: ")  
        try:
            n=int(n)                        # if input is valid value then seaching will be done so store that number 
            inputCheck = False                                                                                                                                                                                            
        except ValueError or TypeError:
            print("Please enter a number")
            time.sleep(0.6)


    print("Searching...")

    l = 0
    h = len(list) - 1 

    while l <= h:
        mid = (l + h) // 2

        if list[mid] == n:
            pos = mid
            print(f"Found at index {pos}")
            break
        else:
            print(n)
            if list[mid] < n:
                l = mid+1           # as index mid has already checked so set l=mid+1
            else:
                h = mid-1           # mid has already checked so set h=mid-1
            
Search(list)

【讨论】：