Question

如何打开文件Stud.txt，然后用“Orange”替换任何出现的“A”？

Answer 1

with open("Stud.txt", "rt") as fin:
    with open("out.txt", "wt") as fout:
        for line in fin:
            fout.write(line.replace('A', 'Orange'))

Answer 2

如果您想要替换同一文件中的字符串，您可能必须将其内容读入本地变量，关闭它，然后重新打开它以进行写入：

我在这个例子中使用the with statement，它在with块终止后关闭文件 - 通常是在最后一个命令完成执行时，或者是异常。

def inplace_change(filename, old_string, new_string):
    # Safely read the input filename using 'with'
    with open(filename) as f:
        s = f.read()
        if old_string not in s:
            print('"{old_string}" not found in {filename}.'.format(**locals()))
            return

    # Safely write the changed content, if found in the file
    with open(filename, 'w') as f:
        s = f.read()
        print('Changing "{old_string}" to "{new_string}" in {filename}'.format(**locals()))
        s = s.replace(old_string, new_string)
        f.write(s)

值得一提的是，如果文件名不同，我们可以使用单个with语句更优雅地完成此操作。

Answer 3

  #!/usr/bin/python

  with open(FileName) as f:
    newText=f.read().replace('A', 'Orange')

  with open(FileName, "w") as f:
    f.write(newText)

Answer 4

像

这样的东西

file = open('Stud.txt')
contents = file.read()
replaced_contents = contents.replace('A', 'Orange')

<do stuff with the result>

Answer 5

with open('Stud.txt','r') as f:
    newlines = []
    for line in f.readlines():
        newlines.append(line.replace('A', 'Orange'))
with open('Stud.txt', 'w') as f:
    for line in newlines:
        f.write(line)

Answer 6

如果您使用的是Linux，只想将dog替换为cat，则可以执行以下操作：

<强>的text.txt：

Hi, i am a dog and dog's are awesome, i love dogs! dog dog dogs!

Linux命令：

sed -i 's/dog/cat/g' test.txt

<强>输出：

Hi, i am a cat and cat's are awesome, i love cats! cat cat cats!

原帖：https://askubuntu.com/questions/20414/find-and-replace-text-within-a-file-using-commands

Answer 7

使用pathlib（https://docs.python.org/3/library/pathlib.html）

from pathlib import Path
file = Path('Stud.txt')
file.write_text(file.read_text().replace('A', 'Orange'))

如果输入文件和输出文件不同，则将read_text和write_text使用两个不同的变量。

如果您希望更改比单个替换更复杂，则可以将read_text的结果分配给一个变量，对其进行处理，然后将新内容保存到另一个变量中，然后使用{{ 1}}。

如果文件很大，则最好不要读取内存中的整个文件，而是按照Gareth Davidson在另一个答案（https://stackoverflow.com/a/4128192/3981273）中的显示逐行处理它，这当然需要使用两个不同的文件进行输入和输出。

Answer 8

最简单的方法是使用正则表达式，假设你想迭代文件中的每一行（你将存储'A'）...

import re

input = file('C:\full_path\Stud.txt), 'r')
#when you try and write to a file with write permissions, it clears the file and writes only #what you tell it to the file.  So we have to save the file first.

saved_input
for eachLine in input:
    saved_input.append(eachLine)

#now we change entries with 'A' to 'Orange'
for i in range(0, len(old):
    search = re.sub('A', 'Orange', saved_input[i])
    if search is not None:
        saved_input[i] = search
#now we open the file in write mode (clearing it) and writing saved_input back to it
input = file('C:\full_path\Stud.txt), 'w')
for each in saved_input:
    input.write(each)

替换文件内容中的字符串

8 个答案: