blocks|key|1034116|text|可能需要检查一下TextWriter类。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1034117|//Open+File
TextWriter+tw+=+new+StreamWriter("file.txt");

//Write+to+file
tw.WriteLine("test+info");

//Close+File
tw.Close();|code-block|syntax|javascript|1034118|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/system.io.textwriter.aspx^0|8|A|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Might want to check out the <a href="http://msdn.microsoft.com/en-us/library/system.io.textwriter.aspx" rel="nofollow noreferrer">TextWriter</a> class. 

<pre><code>//Open File
TextWriter tw = new StreamWriter("file.txt");

//Write to file
tw.WriteLine("test info");

//Close File
tw.Close();
</code></pre>

blocks|key|1249202|text|using+(StreamWriter+w+=+File.AppendText("myFile.txt"))
{
++w.WriteLine("hello");
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1249203|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>using (StreamWriter w = File.AppendText("myFile.txt"))
{
 w.WriteLine("hello");
}
</code></pre>

blocks|key|1034134|text|您可以使用File.AppendAllText来实现此目的：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1034135|File.AppendAllText(@"c:\path\file.txt",+"text+content"+%2B+Environment.NewLine);|code-block|syntax|javascript|1034136|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/ms143356.aspx^0|5|I|5|I|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

You can use <a href="http://msdn.microsoft.com/en-us/library/ms143356.aspx" rel="noreferrer"><code>File.AppendAllText</code></a> for that:

<pre><code>File.AppendAllText(@"c:\path\file.txt", "text content" + Environment.NewLine);
</code></pre>

blocks|key|1034140|text|File.AppendText将做到这一点：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1034141|using+(StreamWriter+w+=+File.AppendText("textFile.txt"))+
{
++++w.WriteLine+("-------HURRAY----------");
++++w.Flush();
}|code-block|syntax|javascript|1034142|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

File.AppendText will do it:

<pre><code>using (StreamWriter w = File.AppendText("textFile.txt")) 
{
 w.WriteLine ("-------HURRAY----------");
 w.Flush();
}
</code></pre>

blocks|key|1249276|text|选择一！但第一个非常简单。最后一个可能是用于文件操作的util：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1249277|//Method+1+(I+like+this)
File.AppendAllLines(
++++"FileAppendAllLines.txt",+
++++new+string[]+{+"line1",+"line2",+"line3"+});

//Method+2
File.AppendAllText(
++++"FileAppendAllText.txt",
++++"line1"+%2B+Environment.NewLine+%2B
++++"line2"+%2B+Environment.NewLine+%2B
++++"line3"+%2B+Environment.NewLine);

//Method+3
using+(StreamWriter+stream+=+File.AppendText("FileAppendText.txt"))
{
++++stream.WriteLine("line1");
++++stream.WriteLine("line2");
++++stream.WriteLine("line3");
}

//Method+4
using+(StreamWriter+stream+=+new+StreamWriter("StreamWriter.txt",+true))
{
++++stream.WriteLine("line1");
++++stream.WriteLine("line2");
++++stream.WriteLine("line3");
}

//Method+5
using+(StreamWriter+stream+=+new+FileInfo("FileInfo.txt").AppendText())
{
++++stream.WriteLine("line1");
++++stream.WriteLine("line2");
++++stream.WriteLine("line3");
}|code-block|syntax|javascript|1249278|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Choice one! But the first is very simple. The last maybe util for file manipulation:

<pre><code>//Method 1 (I like this)
File.AppendAllLines(
 "FileAppendAllLines.txt", 
 new string[] { "line1", "line2", "line3" });

//Method 2
File.AppendAllText(
 "FileAppendAllText.txt",
 "line1" + Environment.NewLine +
 "line2" + Environment.NewLine +
 "line3" + Environment.NewLine);

//Method 3
using (StreamWriter stream = File.AppendText("FileAppendText.txt"))
{
 stream.WriteLine("line1");
 stream.WriteLine("line2");
 stream.WriteLine("line3");
}

//Method 4
using (StreamWriter stream = new StreamWriter("StreamWriter.txt", true))
{
 stream.WriteLine("line1");
 stream.WriteLine("line2");
 stream.WriteLine("line3");
}

//Method 5
using (StreamWriter stream = new FileInfo("FileInfo.txt").AppendText())
{
 stream.WriteLine("line1");
 stream.WriteLine("line2");
 stream.WriteLine("line3");
}
</code></pre>

blocks|key|1249295|text|//display+sample+reg+form+in+notepad.txt
using+(StreamWriter+stream+=+new+FileInfo("D:\\tt.txt").AppendText())//ur+file+location//.AppendText())
{
+++stream.WriteLine("Name+:"+%2B+textBox1.Text);//display+textbox+data+in+notepad
+++stream.WriteLine("DOB+:+"+%2B+dateTimePicker1.Text);//display+datepicker+data+in+notepad
+++stream.WriteLine("DEP:"+%2B+comboBox1.SelectedItem.ToString());
+++stream.WriteLine("EXM+:"+%2B+listBox1.SelectedItem.ToString());
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1249296|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>//display sample reg form in notepad.txt
using (StreamWriter stream = new FileInfo("D:\\tt.txt").AppendText())//ur file location//.AppendText())
{
 stream.WriteLine("Name :" + textBox1.Text);//display textbox data in notepad
 stream.WriteLine("DOB : " + dateTimePicker1.Text);//display datepicker data in notepad
 stream.WriteLine("DEP:" + comboBox1.SelectedItem.ToString());
 stream.WriteLine("EXM :" + listBox1.SelectedItem.ToString());
}
</code></pre>

blocks|key|1249306|text|或者，您可以使用File.AppendAllLines(string,+IEnumerable)|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1249307|File.AppendAllLines(@"C:\Path\file.txt",+new[]+{+"my+text+content"+});|code-block|syntax|javascript|1249308|entityMap|0|LINK|mutability|MUTABLE|url|https://msdn.microsoft.com/en-us/library/dd383691(v=vs.110).aspx^0|8|14|8|14|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

Or you could use <a href="https://msdn.microsoft.com/en-us/library/dd383691(v=vs.110).aspx" rel="noreferrer"><code>File.AppendAllLines(string, IEnumerable&lt;string&gt;)</code></a>

<pre><code>File.AppendAllLines(@"C:\Path\file.txt", new[] { "my text content" });
</code></pre>

blocks|key|1249335|text|技术上最好的方法可能是这里：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1249336|private+static+async+Task+AppendLineToFileAsync([NotNull]+string+path,+string+line)
{
++++if+(string.IsNullOrWhiteSpace(path))+
++++++++throw+new+ArgumentOutOfRangeException(nameof(path),+path,+"Was+null+or+whitepsace.");

++++if+(!File.Exists(path))+
++++++++throw+new+FileNotFoundException("File+not+found.",+nameof(path));

++++using+(var+file+=+File.Open(path,+FileMode.Append,+FileAccess.Write))
++++using+(var+writer+=+new+StreamWriter(file))
++++{
++++++++await+writer.WriteLineAsync(line);
++++++++await+writer.FlushAsync();
++++}
}|code-block|syntax|javascript|1249337|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

The technically best way is probably this here: 

<pre class="lang-cs prettyprint-override"><code>private static async Task AppendLineToFileAsync([NotNull] string path, string line)
{
 if (string.IsNullOrWhiteSpace(path)) 
 throw new ArgumentOutOfRangeException(nameof(path), path, "Was null or whitepsace.");

 if (!File.Exists(path)) 
 throw new FileNotFoundException("File not found.", nameof(path));

 using (var file = File.Open(path, FileMode.Append, FileAccess.Write))
 using (var writer = new StreamWriter(file))
 {
 await writer.WriteLineAsync(line);
 await writer.FlushAsync();
 }
}
</code></pre>

I want to open a text file, append a single line to it, then close it.

Open existing file, append a single line

我想打开一个文本文件，在它后面附加一行，然后关闭它。

问打开现有文件，追加一行
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