在输入中使用计算和字符串。 （Python 2.7）

Question

I'm having this annoying problem in Python 2.7, it won't let me do this

numbers = raw_input(numbers + 1 + ': ')

I want it to print out 'numbers + 1' as a number in the console but.. It comes up with this error message:

Traceback (most recent call last):
  File "F:/Python/Conversation", line 25, in <module>
    numbers = raw_input(numbers + 1 + ': ')
TypeError: unsupported operand type(s) for +: 'int' and 'str'

Is there a solution or just another thing that I can use instead of this? Thanks in advance!

Answer 1

You need to put + and numbers inside a single/double quote; or else, it will be treated as a string concatenation. You got the error because you tried to concatenate/add numbers with 1 .

So, you need to cast 1 to a string, using str( ) . Then, concatenate it with 'numbers + ' and ': '. Like so:

>>> numbers = raw_input('numbers + ' + str(1) + ': ')
numbers + 1: 

However , If you want to replace numbers with number:

>>> numbers = 3
>>> numbers = raw_input(str(numbers + 1) + ': ')
4:

It works because you add the numbers 's value with 1 first. Then, cast the result to string later.

Answer 2

As the error message points out, you cannot add a number and a string. You can add two strings, so try this:

raw_input( str(numbers+1) + ':' )

Answer 3

You need to turn the 1 int value into a string:

numbers = raw_input(numbers + str(1) + ': ')

Alternatively, use string formatting:

numbers = raw_input('{}{}: '.format(numbers, 1))

Or perhaps you wanted to turn numbers into an int first, then the result into a string:

sum = int(numbers) + 1
numbers = raw_input(str(sum) + ': ')