StreamReader.Peek 方法

定义

命名空间:
System.IO
程序集:
mscorlib.dll, System.IO.dll
程序集:
netstandard.dll, System.Runtime.dll
程序集:
System.IO.dll
程序集:
System.Runtime.Extensions.dll
程序集:
mscorlib.dll
程序集:
netstandard.dll
Source:
StreamReader.cs
Source:
StreamReader.cs
Source:
StreamReader.cs
Source:
StreamReader.cs
Source:
StreamReader.cs

返回下一个可用字符，但不使用该字符。

public:
 override int Peek();
public override int Peek();
override this.Peek : unit -> int
Public Overrides Function Peek () As Integer

返回

Int32

一个整数，表示要读取的下一个字符，或者 -1 如果没有要读取的字符，或者流不支持查找。

例外

IOException

出现 I/O 错误。

示例

下面的代码示例从文件读取行，直到到达文件末尾。

using System;
using System.IO;

class Test
{
    
    public static void Main()
    {
        string path = @"c:\temp\MyTest.txt";

        try
        {
            if (File.Exists(path))
            {
                File.Delete(path);
            }

            using (StreamWriter sw = new StreamWriter(path))
            {
                sw.WriteLine("This");
                sw.WriteLine("is some text");
                sw.WriteLine("to test");
                sw.WriteLine("Reading");
            }

            using (StreamReader sr = new StreamReader(path))
            {

                while (sr.Peek() > -1)
                {
                    Console.WriteLine(sr.ReadLine());
                }
            }
        }
        catch (Exception e)
        {
            Console.WriteLine("The process failed: {0}", e.ToString());
        }
    }
}

Imports System.IO
Imports System.Text

Public Class Test

    Public Shared Sub Main()
        Dim path As String = "c:\temp\MyTest.txt"

        Try
            If File.Exists(path) Then
                File.Delete(path)
            End If

            Dim sw As StreamWriter = New StreamWriter(path)
            sw.WriteLine("This")
            sw.WriteLine("is some text")
            sw.WriteLine("to test")
            sw.WriteLine("Reading")
            sw.Close()

            Dim sr As StreamReader = New StreamReader(path)

            Do While sr.Peek() > -1
                Console.WriteLine(sr.ReadLine())
            Loop
            sr.Close()
        Catch e As Exception
            Console.WriteLine("The process failed: {0}", e.ToString())
        End Try
    End Sub
End Class

注解

该方法 Peek 返回一个整数值，以确定文件末尾还是发生了另一个错误。 这样，用户就可以先检查返回的值是否 -1，然后再将其 Char 转换为类型。

此方法重写 TextReader.Peek。

对象的StreamReader当前位置不会更改。Peek

适用于

另请参阅