Question

我正在编写一段代码，需要将数字乘以不同的值，所有用于输入和验证7位数字的代码都有效，但乘法不起作用。这是我的代码。

while True:
    try:
        num = int(input("enter a 7 digit number: "))
        check = len(str(num))

        if check == 7:
            print("This code is valid")
            break

        else:
            num = int(input("enter a number that is only 7 digits: "))

    except ValueError:
        print("you must enter an integer")


num = int(num)        

def multiplication():
    num[0]*3
    num[1]*1
    num[2]*3
    num[3]*1
    num[4]*3
    num[5]*1
    num[6]*3
    return total

multiplication()

当我运行它时，我收到以下错误：

Traceback (most recent call last): 
  File "\\hpdl3802\stuhomefolders$\12waj066\Year 10\Computing\A453\Code\Test v2.py", line 29, in <module> 
    multiplication() 
  File "\\hpdl3802\stuhomefolders$\12waj066\Year 10\Computing\A453\Code\Test v2.py", line 20, in multiplication 
    num[0]*3 
TypeError: 'int' object is not subscriptable

欢迎任何反馈

Answer 1

当然，您的代码可能会以多种方式编写，并进行优化（请查看@Kasravand回答，这很棒），但只需付出最少的努力，这就是我得到的：

while True:
    try:
        num = input("enter a 7 digit number: ")
        check = len(num)
        int(num) # will trigger ValueError if not a number

        if check == 7:
            print("This code is valid")
            break
        else:
            print("bad length, try again")

    except ValueError:
        print("you must enter an integer")

def multiplication(num):
    total  = int(num[0])*3
    total += int(num[1])*1
    total += int(num[2])*3
    total += int(num[3])*1
    total += int(num[4])*3
    total += int(num[5])*1
    total += int(num[6])*3

    return total

print("Answer: ", multiplication(num))

Answer 2

当您将输入数字转换为整数时，您无法在该对象上使用索引，因为整数不支持索引。如果要将数字乘以特定数字，最好在转换为整数之前执行此操作。

首先，请更换以下部分：

num = int(input("enter a number that is only 7 digits: "))

使用：

num = input("enter a number that is only 7 digits: ")

您可以使用repeat模块中的chain和itertools函数来创建重复的数字，然后使用列表推导来计算乘法：

>>> from itertools import repeat, chain
>>> N = 7
>>> li = list(chain.from_iterable(repeat([3, 1], N/2 + 1)))
>>> num = '1290286'
>>> [i * j for i, j in zip(map(int, num), li)]
[3, 2, 27, 0, 6, 8, 18]

Answer 3

如果您必须使用整数而不是输入的列表，则可以执行以下操作之一：

您可以使用整数除法和模数的组合来访问各个数字，例如：

first_digit = num // 1000000 * 3
second_digit = num // 100000 % 10 * 1
# and so on

或者您可以将输入作为字符串获取并访问并转换各个数字：

# [...]
num = input("enter a number that is only 7 digits: ")
# [...]
first_digit = int(num[0]) * 3
second_digit = int(num[1]) * 3

Answer 4

此代码将起作用：

while True:
    try:
        num = int(input("enter a 7 digit number: "))
    except ValueError:
        print("you must enter an integer")

    else:

        if len(str(num)) != 7:
            print("enter a number that is only 7 digits")            
        else:
            break

num = str(num)

def multiplication():
    total = 0 
    for i,m in enumerate([3,1,3,1,3,1,3]):        
       total += int(num[i])*m   # transform the index of text into a integer

    return total

print(multiplication())

Answer 5

这应该有帮助

    num = ''
    check = 0
    while True:
        try:
            num = raw_input("enter a 7 digit number: ")
            check = len(num)

            if check == 7:
                print("This code is valid")
                break

            else:
                print "enter a number that is only 7 digits"

        except ValueError:
            print("you must enter an integer")


    def multiplication():
        total = 0
        for i in range(check):
            if i % 2 == 0:
                total += int(num[i]) * 3
            else:
                total += int(num[i]) * 1

        print total

    multiplication()

变量中的乘法

5 个答案: