当前位置：文江博客话题详情

使用 Python 迭代字符串中的每个字符

发布于 2024-07-13 08:28:24 字数 61 浏览 6 评论 0原文

如何在 Python 中迭代字符串（从字符串中获取每个字符，一次一个，每次通过一个循环）？

原文

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

兰花执着 2024-07-20 08:28:24

正如 Johannes 指出的，

for c in "string":
    #do something with c

您可以使用 for 循环 构造来迭代 python 中的几乎所有内容，

例如，open("file.txt") 返回一个文件对象（并且打开文件），迭代它迭代该文件中的行

with open(filename) as f:
    for line in f:
        # do something with line

如果这看起来像魔术，那么它有点像，但其背后的想法非常简单。

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 循环对其起作用。

只需实现一个定义 next() 方法的迭代器，并在类上实现一个 __iter__ 方法即可使其可迭代。（__iter__ 当然应该返回一个迭代器对象，即定义 next() 的对象

） org/library/stdtypes.html#iterator-types" rel="noreferrer">查看官方文档

As Johannes pointed out,

for c in "string":
    #do something with c

You can iterate pretty much anything in python using the for loop construct,

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

If that seems like magic, well it kinda is, but the idea behind it is really simple.

There's a simple iterator protocol that can be applied to any kind of object to make the for loop work on it.

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())

See official documentation

回复收藏 0 原文

时光与爱终年不遇 2024-07-20 08:28:24

如果您需要在遍历字符串时访问索引，请使用 enumerate()：

>>> for i, c in enumerate('test'):
...     print i, c
... 
0 t
1 e
2 s
3 t

If you need access to the index as you iterate through the string, use enumerate():

>>> for i, c in enumerate('test'):
...     print i, c
... 
0 t
1 e
2 s
3 t

回复收藏 0 原文

-小熊_ 2024-07-20 08:28:24

更简单：

for c in "test":
    print c

Even easier:

for c in "test":
    print c

回复收藏 0 原文

宣告ˉ结束 2024-07-20 08:28:24

为了给出一个更全面的答案，如果你真的想将方钉强行插入圆孔中，那么迭代字符串的 C 方法可以应用于 Python。

i = 0
while i < len(str):
    print str[i]
    i += 1

但话又说回来，当字符串本质上是可迭代的时，为什么要这样做呢？

for i in str:
    print i

Just to make a more comprehensive answer, the C way of iterating over a string can apply in Python, if you really wanna force a square peg into a round hole.

i = 0
while i < len(str):
    print str[i]
    i += 1

But then again, why do that when strings are inherently iterable?

for i in str:
    print i

回复收藏 0 原文

微暖i 2024-07-20 08:28:24

好吧，你也可以做一些像这样有趣的事情，并通过使用 for 循环来完成你的工作

#suppose you have variable name
name = "Mr.Suryaa"
for index in range ( len ( name ) ):
    print ( name[index] ) #just like c and c++

答案是

M r 。 S uryaa

但是，由于 range() 创建了一个序列值列表，因此您可以直接使用名称，

for e in name:
    print(e)

这也会产生相同的结果，而且看起来更好，并且适用于任何序列，如列表、元组和字典。

我们使用了两个内置函数（Python 社区中的 BIF）

1) range() - range() BIF 用于创建索引
示例

for i in range ( 5 ) :
can produce 0 , 1 , 2 , 3 , 4

2) len() - len() BIF 用于找出给定字符串的长度

Well you can also do something interesting like this and do your job by using for loop

#suppose you have variable name
name = "Mr.Suryaa"
for index in range ( len ( name ) ):
    print ( name[index] ) #just like c and c++

Answer is

M r . S u r y a a

However since range() create a list of the values which is sequence thus you can directly use the name

for e in name:
    print(e)

This also produces the same result and also looks better and works with any sequence like list, tuple, and dictionary.

We have used tow Built in Functions ( BIFs in Python Community )

1) range() - range() BIF is used to create indexes
Example

for i in range ( 5 ) :
can produce 0 , 1 , 2 , 3 , 4

2) len() - len() BIF is used to find out the length of given string

回复收藏 0 原文

城歌 2024-07-20 08:28:24

如果您想使用一种更实用的方法来迭代字符串（也许以某种方式对其进行转换），您可以将字符串拆分为字符，对每个字符应用一个函数，然后将生成的字符列表重新连接回字符串。

字符串本质上是字符列表，因此“map”将迭代字符串 - 作为第二个参数 - 将函数 - 第一个参数 - 应用于每个字符。

例如，这里我使用简单的 lambda 方法，因为我想做的只是对字符进行简单的修改：这里，增加每个字符值：

>>> ''.join(map(lambda x: chr(ord(x)+1), "HAL"))
'IBM'

或者更一般地说：

>>> ''.join(map(my_function, my_string))

其中 my_function 接受一个 char 值并返回一个 char 值。

If you would like to use a more functional approach to iterating over a string (perhaps to transform it somehow), you can split the string into characters, apply a function to each one, then join the resulting list of characters back into a string.

A string is inherently a list of characters, hence 'map' will iterate over the string - as second argument - applying the function - the first argument - to each one.

For example, here I use a simple lambda approach since all I want to do is a trivial modification to the character: here, to increment each character value:

>>> ''.join(map(lambda x: chr(ord(x)+1), "HAL"))
'IBM'

or more generally:

>>> ''.join(map(my_function, my_string))

where my_function takes a char value and returns a char value.

回复收藏 0 原文

美煞众生 2024-07-20 08:28:24

这里的几个答案使用范围。 xrange 通常更好，因为它返回一个生成器，而不是一个完全实例化的列表。当内存和/或长度变化很大的可迭代对象可能成为问题时，xrange 更胜一筹。

回复收藏 0 原文

二货你真萌 2024-07-20 08:28:24

您还可以执行以下操作：

txt = "Hello World!"
print (*txt, sep='\n')

这不使用循环，但内部 print 语句会处理它。

* 将字符串解包到列表中并将其发送到 print 语句

sep='\n' 将确保下一个字符打印在新行上

输出将是：

H
e
l
l
o
 
W
o
r
l
d
!

如果您确实需要循环语句，那么正如其他人提到的，您可以使用 for 循环，如下所示：

for x in txt: print (x)

You can also do the following:

txt = "Hello World!"
print (*txt, sep='\n')

This does not use loops but internally print statement takes care of it.

* unpacks the string into a list and sends it to the print statement

sep='\n' will ensure that the next char is printed on a new line

The output will be:

H
e
l
l
o
 
W
o
r
l
d
!

If you do need a loop statement, then as others have mentioned, you can use a for loop like this:

for x in txt: print (x)

回复收藏 0 原文

凉薄对峙 2024-07-20 08:28:24

如果您曾经遇到过需要使用 __next__() 获取单词的下一个字符的情况，请记住创建一个 string_iterator 并迭代它而不是 < code>原始字符串（它没有 __next__() 方法）

在此示例中，当我找到 char = [ 时，我会继续查找下一个单词虽然我找不到 ]，所以我需要

在这里使用 __next__ 对字符串进行 for 循环没有帮助

myString = "'string' 4 '['RP0', 'LC0']' '[3, 4]' '[3, '4']'"
processedInput = ""
word_iterator = myString.__iter__()
for idx, char in enumerate(word_iterator):
    if char == "'":
        continue

    processedInput+=char

    if char == '[':
        next_char=word_iterator.__next__()
        while(next_char != "]"):
          processedInput+=next_char
          next_char=word_iterator.__next__()
        else:
          processedInput+=next_char

If you ever run in a situation where you need to get the next char of the word using __next__(), remember to create a string_iterator and iterate over it and not the original string (it does not have the __next__() method)

In this example, when I find a char = [ I keep looking into the next word while I don't find ], so I need to use __next__

here a for loop over the string wouldn't help

myString = "'string' 4 '['RP0', 'LC0']' '[3, 4]' '[3, '4']'"
processedInput = ""
word_iterator = myString.__iter__()
for idx, char in enumerate(word_iterator):
    if char == "'":
        continue

    processedInput+=char

    if char == '[':
        next_char=word_iterator.__next__()
        while(next_char != "]"):
          processedInput+=next_char
          next_char=word_iterator.__next__()
        else:
          processedInput+=next_char

回复收藏 0 原文

~没有更多了~