Python 从 if 语句调用函数

Question

I want to sum up the numbers taken by raw_input(">") but instead of giving me the sum when I run the code on the python shell, it gives me the numbers paired. That would be: if I give 4 to answer and 5 to answer2 on the input, it will return 45 instead of 9. Please help me.

from sys import argv

def sum(num1, num2):
    result =(num1 + num2)
    return result


print ' I wanna know your two results'
answer = raw_input(">")
answer2 = raw_input(">")

real_answer = sum(answer, answer2)
print real_answer

Answer 1

You need to convert to integers first:

answer = int(raw_input(">"))
answer2 = int(raw_input(">"))

or keep them the same and do this:

real_answer = sum(map(int, (answer, answer2)))

or

real_answer = sum(int(answer), int(answer2))

With only two numbers, though, you don't need sum() :

real_answer = int(answer) + int(answer2)

Answer 2

It's because the answers are being read as strings, and for strings the addition operator concatenates them. You can fix it by changing the input lines to:

answer = int(raw_input(">"))
answer2 = int(raw_input(">"))

This converts the strings to integers before assigning them to answer and answer2 .

If you want to support floating point numbers (eg 1.2 ), change the int to float .