Question

伙计们和女孩们，我刚开始学习使用python进行编码，并且正在构建一个非常基本的百分比计算器，以使思维方式发生变化。

我在运行程序成功通过时遇到问题：

#Percentage Calculator

print('Enter value of percent: ') #prompt user for input of percent value
percent = input() #gain user input about percent *stored as 'str'
percent = int(percent) #store and convert user input into an 'int' from 'str' for use in line 11

print('Enter value of percentaged number: ') #prompt user for input of percentaged number value
percentagedNum = input() #gain user input on percentaged number *stored as 'str'
percentagedNum = int(percentagedNum) #store and convert value from 'str' into 'int'

answer = percent / percentagedNum #calculate percentage formula

print(percent + '% of ' + percentagedNum + ' is ' + answer) #prompt user with answer

此外，回溯：

Traceback (most recent call last):
  File "C:\Program Files\JetBrains\PyCharm Community Edition 2020.1\plugins\python-ce\helpers\pydev\pydevd.py", line 1438, in _exec
    pydev_imports.execfile(file, globals, locals)  # execute the script
  File "C:\Program Files\JetBrains\PyCharm Community Edition 2020.1\plugins\python-ce\helpers\pydev\_pydev_imps\_pydev_execfile.py", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "C:/Users/Custom/PycharmProjects/PercentageCalculator/main", line 12, in <module>
    print(percent + '% of ' + percentagedNum + ' is ' + answer)
TypeError: unsupported operand type(s) for +: 'int' and 'str'

我觉得这是在最终的print（）函数调用中混合使用字符串，整数和浮点数的连接问题。

对此深表感谢，非常感谢，感谢你们为帮助社区所做的一切。很多爱。

Answer 1

您需要首先将数字转换为字符串。您可以明确地做到这一点：

print(str(percent) + '% of ' + str(percentagedNum) + ' is ' + str(answer))

或者您可以让Python f字符串来处理它：

print(f'{percent} % of {percentagedNum} is {answer}')

您尝试的操作不起作用的原因是+运算符根据给出的内容而得出不同的结果。如果两侧都有字符串，则将其串联：

>>> "foo" + "bar"
"foobar"

如果两边都有整数，则将它们相加：

>>> 5 + 3
8

混合输入类型时，不确定应该做什么。

Answer 2

在您的print语句中，确保使用str()：str(percent)等将包含数字的变量转换为字符串。

实际上，这是开始使用Python时的经典错误。

将字符串与整数和浮点数连接？

2 个答案: