类型错误：+ 不支持的操作数类型：“int”和“list”答案

【问题标题】：TypeError: unsupported operand type(s) for +: 'int' and 'list'类型错误：+ 不支持的操作数类型：“int”和“list”
【发布时间】：2017-03-03 10:15:48
【问题描述】：

我的二进制搜索函数代码不断收到此错误

ex = [3, 4, 19, 42, 53, 23, 5, 8, 20] #list used
number = input("What number do you want to find?: ")
length = len(ex) - 1
first = 0
last = [len(ex)]
done = False
while done == False:
    for i in range(length):
        if ex[i] > ex[i+1]:
            sort = False
            ex[i], ex[i+1] = ex[i+1], ex[i] #flips the numbers in the list
        else:
            print (ex)
            mid = first + last / 2
            found = [ex(mid)]
            if number > found:
                first == mid
            if number < found:
                last == mid
            if number == found:
                print ("number found")
                print (str(found))

问题似乎是 mid = first + last / 2 等式...

【问题讨论】：

您已将last 定义为[len(ex)]，所以last 确实是一个列表。
您在 else 语句中遇到了与 found 类似的问题。
这不是您要寻找的答案，但请记住，布尔值不需要使用== 检查，而是可以使用while not done 表示法来简化您的代码。

标签： python list int

【解决方案1】：

嘿，我刚刚修复了您的代码并在更改中添加了 cmets :) 但是您的代码将进入无限循环，因为您从未将 done 设置为 True

ex = [3, 4, 19, 42, 53, 23, 5, 8, 20] #list used
number = input("What number do you want to find?: ")
length = len(ex) - 1
first = 0
last = len(ex) #the square brackets created a list with only the length as one Element.
done = False
while done == False:
    for i in range(length):
        if ex[i] > ex[i+1]:
            sort = False
            ex[i], ex[i+1] = ex[i+1], ex[i] #flips the numbers in the list
        else:
            print (ex)
            mid = first + int(last / 2) #python creates a float as result of div
            found = ex[mid] # the see command above and you need to use square brackets to access list elements via index...
            if number > found:
                first == mid
            if number < found:
                last == mid
            if number == found:
                print ("number found")
                print (str(found))

【讨论】：

【解决方案2】：

ex = [3, 4, 19, 42, 53, 23, 5, 8, 20] #list used
number = int(input("What number do you want to find?: "))
length = len(ex) - 1
first = 0
last = len(ex)-1;
done = False
#Sort the list first
ex.sort();
#Binary Search
while first > last :
            mid = int((first + last) / 2)
            found = ex[mid]
            if number > found:
                first = mid
            if number < found:
                last = mid
            if number == found:
                print ("number found")
                print (str(found))
                done=True;
                break;
if done == False :
    print("Number not found")

【讨论】：