[英]How to read and write to file at the same time in c#
我需要使用文件來決定綁定數據。 因此,最初我創建一個包含值“ NO”的文件。 第一次讀取代碼時,它將數據綁定到中繼器上以顯示,然后將文件中的值更改為“是”。 當它再次運行(由於重新加載頁面)時,它讀取值“ YES”,表示數據已被綁定,它將不會再次綁定該數據,並且會將文件內容更改為原始的“ NO”並完成運行。
這是我嘗試過的:
// Use file to make binding data decision,
// avoid duplicate binding due to page reload:
using (var fileStream =
File.Open(Server.MapPath("~/binddecision.txt"), FileMode.Open))
{
// read from the file
using (var streamReader = new StreamReader(fileStream))
{
string line = streamReader.ReadLine();
if (line == "NO")
{
companyRepeater.DataSource = companies1;
companyRepeater.DataBind();
LinkRepeater.DataSource = urls;
LinkRepeater.DataBind();
fileStream.SetLength(0); // truncate the file
// If now is not record a loop yet, then write YES to the file
using (var streamWriter = new StreamWriter(fileStream))
{
streamWriter.WriteLine("YES");
}
}
else
{
streamReader.Close();
// If now is a loop then write NO to the file
using (var streamWriter = new StreamWriter(fileStream))
{
streamWriter.WriteLine("NO");
}
}
}
}
但是它仍然顯示有關使用沖突的流的錯誤。 我在Google上閱讀了一些方法,但未能針對該算法實現它。
有人可以幫我嗎?
刪除行streamReader.Close(); 緊接着else {應該是固定的。。無論如何,如果您確實要關閉streamReader,則必須再次打開文件流
fileStream = File.Open(“ test.txt”,FileMode.Open);
當然,您可能希望將fileStream用作局部變量,而不要使用。
嘗試
File.Open(Server.MapPath("~/binddecision.txt"), FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite)
這是一個簡化的示例:
using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
class Program
{
static void Main(string[] args)
{
// Use file to make binding data decision,
// avoid duplicate binding due to page reload:
using (var fileStream =
File.Open("a.txt", FileMode.Open, FileAccess.ReadWrite, FileShare.ReadWrite))
{
// read from the file
var streamReader = new StreamReader(fileStream);
string line = streamReader.ReadLine();
if (line == "NO")
{
using (var streamWriter = new StreamWriter(fileStream))
{
streamWriter.WriteLine("YES");
streamWriter.Close();
}
}
else
{
// If now is a loop then write NO to the file
using (var streamWriter = new StreamWriter(fileStream))
{
streamWriter.WriteLine("NO");
streamWriter.Close();
}
}
}
}
}
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