C# 如何在编写文件时声明文件大小限制

我是C#的新手，想问一下如何将特定的文件限制设置为逗号分隔的文件。我将使用它们的场景如下

const int sizeLimitInBytes = 500*1024*1024;

using (var stream = new FileStream("data.csv", FileMode.Append))
using (var writer = new StreamWriter(stream))
{
    // if the file is newly created then write the csv column names in the first line
    if (stream.Position == 0) 
    {
       writer.WriteLine("Name, Age, Job, Address");
    }

    foreach (var currentData in allData)
    {
        if (stream.Position > sizeLimitInBytes)
        {
            break;
        }
        writer.WriteLine("..."); // write data seperated by commas
    }
}

在写入CSV输出文件之前，我需要检查特定路径/驱动器上是否存在现有CSV文件

在方法运行时，如何使其在超过文件大小限制（最好是500 MB的CSV文件大小）之前停止写入

这是我目前使用的代码：

if (!File.Exists(newFileName))
{
    File.WriteAllText(newFileName, clientheader);
    //File.WriteAllText(logFileName, logfileheader);
}
else
{
    File.AppendAllText(newFileName, clientheader);
    // File.AppendAllText(logFileName, logfileheader);
}

const int sizeLimitInBytes = 500*1024*1024;

using (var stream = new FileStream("data.csv", FileMode.Append))
using (var writer = new StreamWriter(stream))
{
    // if the file is newly created then write the csv column names in the first line
    if (stream.Position == 0) 
    {
       writer.WriteLine("Name, Age, Job, Address");
    }

    foreach (var currentData in allData)
    {
        if (stream.Position > sizeLimitInBytes)
        {
            break;
        }
        writer.WriteLine("..."); // write data seperated by commas
    }
}

您可以使用流（FileStream）来写入csv数据，并通过检查流的Position属性来检查当前大小。假设allData数组中有要写入csv文件的数据（例如名称、年龄等），则其工作原理如下：

const int sizeLimitInBytes = 500*1024*1024;

using (var stream = new FileStream("data.csv", FileMode.Append))
using (var writer = new StreamWriter(stream))
{
    // if the file is newly created then write the csv column names in the first line
    if (stream.Position == 0) 
    {
       writer.WriteLine("Name, Age, Job, Address");
    }

    foreach (var currentData in allData)
    {
        if (stream.Position > sizeLimitInBytes)
        {
            break;
        }
        writer.WriteLine("..."); // write data seperated by commas
    }
}

使用FileMode.Append写入文件末尾（如果存在）。否则它将创建一个

const int sizeLimitInBytes = 500*1024*1024;

using (var stream = new FileStream("data.csv", FileMode.Append))
using (var writer = new StreamWriter(stream))
{
    // if the file is newly created then write the csv column names in the first line
    if (stream.Position == 0) 
    {
       writer.WriteLine("Name, Age, Job, Address");
    }

    foreach (var currentData in allData)
    {
        if (stream.Position > sizeLimitInBytes)
        {
            break;
        }
        writer.WriteLine("..."); // write data seperated by commas
    }
}

StreamWriter使用缓冲（缓冲区大小为4 KB），因此检查是否超过了限制并不完全准确，但对于500 MB的限制来说，这并不重要

const int sizeLimitInBytes = 500*1024*1024;

using (var stream = new FileStream("data.csv", FileMode.Append))
using (var writer = new StreamWriter(stream))
{
    // if the file is newly created then write the csv column names in the first line
    if (stream.Position == 0) 
    {
       writer.WriteLine("Name, Age, Job, Address");
    }

    foreach (var currentData in allData)
    {
        if (stream.Position > sizeLimitInBytes)
        {
            break;
        }
        writer.WriteLine("..."); // write data seperated by commas
    }
}

---

如果您希望将所有内容一次性写入文件，则可以使用MemoryStream而不是FileStream，然后使用file.writealBytes将流中的字节转储到文件中。

我遇到了类似的问题，创建的文件仅包含有限的字符。我找到了解决方案，并在创建文件时尝试使用关键字。现在，文件以最大大小创建

const int sizeLimitInBytes = 500*1024*1024;

using (var stream = new FileStream("data.csv", FileMode.Append))
using (var writer = new StreamWriter(stream))
{
    // if the file is newly created then write the csv column names in the first line
    if (stream.Position == 0) 
    {
       writer.WriteLine("Name, Age, Job, Address");
    }

    foreach (var currentData in allData)
    {
        if (stream.Position > sizeLimitInBytes)
        {
            break;
        }
        writer.WriteLine("..."); // write data seperated by commas
    }
}

using(StreamWriter sw = new StreamWriter(fs))
{
    ArrayList chartList = GetChart(maintNode);    
    foreach (var line in chartList)
    {
        sw.WriteLine(line);
    }
}

---

发件人：

查看

文件。对于问题的第一部分，存在
：。在跟踪您写入的数据量方面，一个简单的方法是统计您写入的字符数，因为每个字符有两个字节。非常感谢。您已经有了哪些用于写入CSV文件的代码？首先将其添加到您的问题中。@Noelskie，将您正在使用的代码添加到原始问题中，而不是添加到注释中。请参见此处：以字节为单位计算字符串的长度。您能详细说明一下这个答案吗。根据你提供的答案，我不明白。你能举个例子说明你是怎么解决的吗？这个答案并没有回答OP的问题。
const int sizeLimitInBytes = 500*1024*1024;

using (var stream = new FileStream("data.csv", FileMode.Append))
using (var writer = new StreamWriter(stream))
{
    // if the file is newly created then write the csv column names in the first line
    if (stream.Position == 0) 
    {
       writer.WriteLine("Name, Age, Job, Address");
    }

    foreach (var currentData in allData)
    {
        if (stream.Position > sizeLimitInBytes)
        {
            break;
        }
        writer.WriteLine("..."); // write data seperated by commas
    }
}