python - 如何将字符串添加到特定行

Question

我有一个包含 50 行的文件。我如何使用 python/linux 将字符串“-----”添加到特定行，例如第 20 行？

Answer 1

你试过这样的事情吗？

exp = 20 # the line where text need to be added or exp that calculates it for ex %2

with open(filename, 'r') as f:
    lines = f.readlines()

with open(filename, 'w') as f:
    for i,line in enumerate(lines):
        if i == exp:
            f.write('------')
        f.write(line)

如果您需要编辑差异行数，您可以通过这种方式更新上面的代码:

def update_file(filename, ln):
    with open(filename, 'r') as f:
        lines = f.readlines()

    with open(filename, 'w') as f:
        for idx,line in enumerate(lines):
            (idx in ln and f.write('------'))
            f.write(line)