TypeError：无法连接'str'和'int'对象 [英] TypeError: cannot concatenate 'str' and 'int' objects

问题描述

我现在正在学习Python，是的！无论如何，我有小问题。我在这里看不到问题：

I'm learning Python now, yay! Anyway, I have small problem. I don't see problem in here:

x = 3
y = 7
z = 2

print "I told to the Python, that the first variable is %d!" % x
print "Anyway, 2nd and 3rd variables sum is %d. :)" % y + z

但Python认为不同 - TypeError：无法连接'str'和'int'对象。

But Python thinks different - TypeError: cannot concatenate 'str' and 'int' objects.

为什么会这样？我没有将任何变量设置为字符串......就像我看到的那样。

Why is that so? I haven't setted any variable as string... as much as I see.

推荐答案

％ 的优先级高于 + ，因此 s％y + z 被解析为（s％y）+ z 。

% has a higher precedence than +, so s % y + z is parsed as (s % y) + z.

如果 s 是一个字符串，然后 s％x 是一个字符串，（s％y）+ z 尝试添加一个字符串string（ s％y 的结果）和一个整数（值 z ）。

If s is a string, then s % x is a string, and (s % y) + z attempts to add a string (the result of s % y) and an integer (the value of z).

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