问题描述
在 C++ 中，我可以像这样遍历 std::string:
In C++, I can iterate over an std::string like this:
std::string str = "Hello World!";
for (int i = 0; i < str.length(); ++i)
{
std::cout << str[i] << std::endl;
}
如何在 Python 中迭代字符串?
How do I iterate over a string in Python?
推荐答案
正如 Johannes 指出的那样，
As Johannes pointed out,
for c in "string":
#do something with c
您可以使用 for 循环 构造在 python 中迭代几乎任何东西，
You can iterate pretty much anything in python using the for loop construct,
例如，open("file.txt") 返回一个文件对象(并打开文件)，遍历它会遍历该文件中的行
for example, open("file.txt") returns a file object (and opens the file), iterating over it iterates over lines in that file
with open(filename) as f:
for line in f:
# do something with line
如果这看起来很神奇，那么它有点像，但它背后的想法真的很简单.
If that seems like magic, well it kinda is, but the idea behind it is really simple.
有一个简单的迭代器协议可以应用于任何类型的对象，以使 for 循环在其上工作.
There's a simple iterator protocol that can be applied to any kind of object to make the for loop work on it.
只需实现一个定义 next() 方法的迭代器，并在一个类上实现一个 __iter__ 方法以使其可迭代.(__iter__当然应该返回一个迭代器对象，即定义next()的对象)
Simply implement an iterator that defines a next() method, and implement an __iter__ method on a class to make it iterable. (the __iter__ of course, should return an iterator object, that is, an object that defines next())
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