如何使用python3搜索和替换文件中的文本?

这是我的代码:

import os
import sys
import fileinput

print ("Text to search for:")
textToSearch = input( "> " )

print ("Text to replace it with:")
textToReplace = input( "> " )

print ("File to perform Search-Replace on:")
fileToSearch  = input( "> " )
#fileToSearch = 'D:\dummy1.txt'

tempFile = open( fileToSearch, 'r+' )

for line in fileinput.input( fileToSearch ):
    if textToSearch in line :
        print('Match Found')
    else:
        print('Match Not Found!!')
    tempFile.write( line.replace( textToSearch, textToReplace ) )
tempFile.close()


input( '\n\n Press Enter to exit...' )

输入文件:

hi this is abcd hi this is abcd
This is dummy text file.
This is how search and replace works abcd

当我在上面的输入文件中搜索并将“ram”替换为“abcd”时,它就像一个咒语。但当我反过来做,即替换'abcd'由'ram',一些垃圾字符被留在最后。

将'abcd'替换为'ram'

hi this is ram hi this is ram
This is dummy text file.
This is how search and replace works rambcd

当前回答

正如Jack Aidley发布的和J.F. Sebastian指出的那样,这个代码是行不通的:

 # Read in the file
filedata = None
with file = open('file.txt', 'r') :
  filedata = file.read()

# Replace the target string
filedata.replace('ram', 'abcd')

# Write the file out again
with file = open('file.txt', 'w') :
  file.write(filedata)`

但这段代码将工作(我已经测试过了):

f = open(filein,'r')
filedata = f.read()
f.close()

newdata = filedata.replace("old data","new data")

f = open(fileout,'w')
f.write(newdata)
f.close()

使用此方法,fileein和fileout可以是同一个文件,因为Python 3.3将在打开进行写入时覆盖该文件。

其他回答

你可以这样做替换

f1 = open('file1.txt', 'r')
f2 = open('file2.txt', 'w')
for line in f1:
    f2.write(line.replace('old_text', 'new_text'))
f1.close()
f2.close()

正如Jack Aidley发布的和J.F. Sebastian指出的那样,这个代码是行不通的:

 # Read in the file
filedata = None
with file = open('file.txt', 'r') :
  filedata = file.read()

# Replace the target string
filedata.replace('ram', 'abcd')

# Write the file out again
with file = open('file.txt', 'w') :
  file.write(filedata)`

但这段代码将工作(我已经测试过了):

f = open(filein,'r')
filedata = f.read()
f.close()

newdata = filedata.replace("old data","new data")

f = open(fileout,'w')
f.write(newdata)
f.close()

使用此方法,fileein和fileout可以是同一个文件,因为Python 3.3将在打开进行写入时覆盖该文件。

你也可以使用pathlib。

from pathlib2 import Path
path = Path(file_to_search)
text = path.read_text()
text = text.replace(text_to_search, replacement_text)
path.write_text(text)

您的问题源于读取和写入同一个文件。与其打开fileToSearch进行写入,不如打开一个实际的临时文件,然后在您完成并关闭tempFile之后,使用os。rename将新文件移动到fileToSearch上。

我试过用readline代替read

with open('dummy.txt','r') as file:
    list = file.readlines()
print(f'before removal {list}')
for i in list[:]:
        list.remove(i)

print(f'After removal {list}')
with open('dummy.txt','w+') as f:
    for i in list:
        f.write(i)