C# - 随机写入文件 - 在第一行之前写入第二行
我正在尝试使用 FileStream 写入文件，并且想要写入第二行，然后写入第一行。我在编写第二行后使用 Seek() 返回开头，然后编写第一行。它替换第二行（或其中一部分，具体取决于第一行的长度。）我如何不让它替换第二行？
var fs = new FileStream("my.txt", FileMode.Create);
byte[] stringToWrite = Encoding.UTF8.GetBytes("string that should be in the end");
byte[] stringToWrite2 = Encoding.UTF8.GetBytes("first string\n");
fs.Write(stringToWrite, 0, stringToWrite.Length);
fs.Seek(0, SeekOrigin.Begin);
fs.Write(stringToWrite2, 0, stringToWrite2.Length);
文件中写入以下内容：
first string
hould be in the end
我希望它是
first string
string that should be in the end
谢谢
I am trying to write to a file using a FileStream and want to write the second line and then write the first line. I use Seek() to go back to the beginning after writing the second line and then write the first line. It replaces the second line ( or part of it depending on the length of the first line.) How do I not make it replace the second line?
var fs = new FileStream("my.txt", FileMode.Create);
byte[] stringToWrite = Encoding.UTF8.GetBytes("string that should be in the end");
byte[] stringToWrite2 = Encoding.UTF8.GetBytes("first string\n");
fs.Write(stringToWrite, 0, stringToWrite.Length);
fs.Seek(0, SeekOrigin.Begin);
fs.Write(stringToWrite2, 0, stringToWrite2.Length);
Following is written to the file:
first string
hould be in the end
I want it to be
first string
string that should be in the end
Thanks
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您首先需要在文件中查找等于第一个字符串的长度。
另外，不要忘记处置您的流（
using）。You first need to seek into the file equal to the length of the first string.
Also, don't forget to dispose of your stream (
using).您无法插入文件并将现有内容推回。您只能覆盖或扩展。
因此，在您知道文件前面所有内容的内容之前，您无法写入该文件的一部分。
You can't insert into a file and push the existing contents back. You can only overwrite or extend.
You therefore can't write a piece of the file until you know the contents of all that precedes it.
根据您想要实现的目标，您可能需要写入两个不同的文件，其中一个是临时文件。
如果这是更大的解决方案中反复出现的要求，也许您想要的是某种数据库的？也许是基于文件的数据库，例如 SqlLite 或 BerkeleyDb。
此处讨论了类似的问题。
Depending on what you are trying to achieve, you may need to write to two different files, one being a temporary file.
If this a recurring requirement in a bigger solution, maybe what you want is some kind of database? Maybe a file-based database like SqlLite or BerkeleyDb.
A similar problem is discussed here.