Question

我正在制作打开txt文件并用给定行的1替换前0的程序。现在，它仅打印已编辑的行，但我希望它打印所有行。我正在使用python 3.1。

line_number = 3
with open(filename, "r") as f:
    number = 0
    for line in f:
        number += 1
        if line_number == number:
            content = line.replace("0","1",1)
savefile = filename[:4] + ".tmp"
with open(savefile, "w") as f:
    f.write(content)
os.remove(filename)
os.rename(savefile, filename)

文本文件：

0 Dog
0 Cat
0 Giraffe
0 Leopard
0 Bear

Answer 1

您需要将每个未更改的行写入savefile：

import os
filename = 'input.txt'

line_number = 3
savefile = filename[:4] + ".tmp"
with open(filename, "r") as f:
    with open(savefile, "w") as fout:
        number = 0
        for line in f:
            number += 1
            if line_number == number:
                content = line.replace("0","1",1)
                fout.write(content)
            else:
                # Write unchanged lines here
                fout.write(line)
os.remove(filename)
os.rename(savefile, filename)

Answer 2

您尝试过这样的事情吗？

filename = "./test.txt"

with open(filename) as f:
    lines = f.readlines()
# the element with index 2 is the 3-th element
lines[2] = lines[2].replace("0","1",1)

with open(filename, 'w') as f:
        [f.write(line) for line in lines]

输出（./test.txt）：

0 Dog
0 Cat
1 Giraffe
0 Leopard
0 Bear

您可以读取文件并将其保存到列表中。然后，您可以对列表中的每个项目（或特定元素）执行特定操作，并将结果保存在同一文件中。您不需要.tmp文件，也不需要删除和重命名文件。

修改：
fileinput还有另一种方法（感谢@PeterWood）

import fileinput

with fileinput.input(files=('test.txt',), inplace=True) as f:
    for line in f:
        if fileinput.lineno() is 3:
            print(line.replace("0", "1", 1).strip())
        else:
            print(line.strip())

txt文件中的Python编辑行

2 个答案: