.net 添加文本到文本文件

StreamWriter没有Append方法，只能用seek设置位置，然后stream.WriteLine() 或stream.write(),这样会覆盖原来的文本。

找到需要添加行的位置，把要添加的行+原来后面所有的内容，再write（）

 

void AppendText(FileInfo file)

{

FileStream fileStream = file.Open(FileMode.Open, FileAccess.ReadWrite);

int postion = 0;

StreamReader reader = new StreamReader(fileStream);

 

string content = reader.ReadToEnd();

StringBuilder builder = new StringBuilder();

fileStream.Seek(0, SeekOrigin.Begin);

postion = content.IndexOf("using");

string nextString = content.Substring(postion);

string x = "using System;\n"+nextString ;

fileStream.Seek(postion , SeekOrigin.Begin);

StreamWriter writer = new StreamWriter(fileStream);

writer.WriteLine(x);

writer.Flush();

fileStream.Close();

}