我正在閱讀自學程序員 ch17 這本書，但我不明白為什么這不起作用

Question

匹配多行

import re
zen = """Although never is often better than *right* now. If the implementation
is hard to explain, it's a bad idea. If the implementation is easy to explain, it
may be a good idea. Namespaces are one honking great idea -- let's do more of those!
m = re.findall("^If", zen, re.MULTILINE)
print(m)

[if,if]是應該打印的，但我得到的只是[]

Answer 1

您沒有正確復制示例。 當您使用re.MULTILINE標志時， ^匹配行的開頭，因此這只匹配If當它位於行的開頭時。 我沒有這本書，但我認為它的每個句子都有自己的一行。

import re
zen = """Although never is often better than *right* now. 
If the implementation is hard to explain, it's a bad idea. 
If the implementation is easy to explain, it may be a good idea. 
Namespaces are one honking great idea -- let's do more of those!"""
m = re.findall("^If", zen, re.MULTILINE)
print(m)

Answer 2

脫字符^表示If必須位於行首。 刪除它，你會得到你想要的答案。

import re
zen = """Although never is often better than *right* now. If the implementation
is hard to explain, it's a bad idea. If the implementation is easy to explain, it
may be a good idea. Namespaces are one honking great idea -- let's do more of those! """
m = re.findall("If", zen, re.MULTILINE)
print(m)

Answer 3

Python 的實際禪宗每行有一個句子：

zen = """
Although never is often better than *right* now.
If the implementation is hard to explain, it's a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea -- let's do more of those!"""
m = re.findall("^If", zen, re.MULTILINE)
print(m)