Marshal.ReadByte Method

Definition

从非托管内存读取单个字节。Reads a single byte from unmanaged memory. 支持从未对齐的内存位置进行读取。Reading from unaligned memory locations is supported.

Overloads

ReadByte(IntPtr, Int32)

从非托管内存按给定的偏移量(或索引)读取单个字节。Reads a single byte at a given offset (or index) from unmanaged memory.

ReadByte(Object, Int32)

从非托管内存按给定的偏移量(或索引)读取单个字节。Reads a single byte at a given offset (or index) from unmanaged memory.

ReadByte(IntPtr)

从非托管内存读取单个字节。Reads a single byte from unmanaged memory.

ReadByte(IntPtr, Int32)

从非托管内存按给定的偏移量(或索引)读取单个字节。Reads a single byte at a given offset (or index) from unmanaged memory.

public:
 static System::Byte ReadByte(IntPtr ptr, int ofs);
[System.Security.SecurityCritical]
public static byte ReadByte (IntPtr ptr, int ofs);
public static byte ReadByte (IntPtr ptr, int ofs);
static member ReadByte : nativeint * int -> byte
Public Shared Function ReadByte (ptr As IntPtr, ofs As Integer) As Byte

Parameters

ptr
IntPtr

非托管内存中开始读取的基址。The base address in unmanaged memory from which to read.

ofs
Int32

额外的字节偏移量,在读取前添加到 ptr 参数中。An additional byte offset, which is added to the ptr parameter before reading.

Returns

Byte

从非托管内存按给定的偏移量读取的字节。The byte read from unmanaged memory at the given offset.

Attributes

Exceptions

基址 (ptr) 加上偏移字节 (ofs) 可产生空或无效地址。Base address (ptr) plus offset byte (ofs) produces a null or invalid address.

Examples

下面的示例演示如何使用 ReadByteWriteByte 方法读取和写入非托管数组。The following example demonstrates how to read and write to an unmanaged array using the ReadByte and WriteByte methods.

static void ReadWriteByte()
{
    // Allocate unmanaged memory. 
    int elementSize = 1;
    IntPtr unmanagedArray = Marshal.AllocHGlobal(10 * elementSize);

    // Set the 10 elements of the C-style unmanagedArray
    for (int i = 0; i < 10; i++)
    {
        Marshal.WriteByte(unmanagedArray, i * elementSize, ((Byte)(i + 1)));
    }
    Console.WriteLine("Unmanaged memory written.");

    Console.WriteLine("Reading unmanaged memory:");
    // Print the 10 elements of the C-style unmanagedArray
    for (int i = 0; i < 10; i++)
    {
        Console.WriteLine(Marshal.ReadByte(unmanagedArray, i * elementSize));
    }

    Marshal.FreeHGlobal(unmanagedArray);

    Console.WriteLine("Done. Press Enter to continue.");
    Console.ReadLine();
}
Sub ReadWriteByte()
    ' Allocate unmanaged memory. 
    Dim elementSize As Integer = 1
    Dim unmanagedArray As IntPtr = Marshal.AllocHGlobal(10 * elementSize)

    ' Set the 10 elements of the C-style unmanagedArray
    For i As Integer = 0 To 9
        Marshal.WriteByte(unmanagedArray, i * elementSize, CType(i + 1, Byte))
    Next i
    Console.WriteLine("Unmanaged memory written.")

    Console.WriteLine("Reading unmanaged memory:")
    ' Print the 10 elements of the C-style unmanagedArray
    For i As Integer = 0 To 9
        Console.WriteLine(Marshal.ReadByte(unmanagedArray, i * elementSize))
    Next i

    Marshal.FreeHGlobal(unmanagedArray)

    Console.WriteLine("Done. Press Enter to continue.")
    Console.ReadLine()
End Sub

下面的示例演示如何使用 ReadByte 方法读取非托管字符的值。The following example demonstrates how to use the ReadByte method to read the value of an unmanaged character.


using namespace System;
using namespace System::Runtime::InteropServices;



void main()
{
    // Create an unmanaged byte.
    const char * myString = "bB";

    // Read the second character of the c string as a managed byte.
        Byte ^ myManagedByte = Marshal::ReadByte((IntPtr) (char *) myString, 1);

    // Display the byte to the console.
    Console::WriteLine(myManagedByte);
}

Remarks

ReadByte 实现与非托管 C 样式字节数组的直接交互,消除将整个非托管数组(使用 Marshal.Copy)复制到单独托管数组的开销,然后再读取其元素值。ReadByte enables direct interaction with an unmanaged C-style byte array, eliminating the expense of copying an entire unmanaged array (using Marshal.Copy) to a separate managed array before reading its element values.

支持从未对齐的内存位置进行读取。Reading from unaligned memory locations is supported.

See also

ReadByte(Object, Int32)

Warning

This API is now obsolete.

从非托管内存按给定的偏移量(或索引)读取单个字节。Reads a single byte at a given offset (or index) from unmanaged memory.

public:
 static System::Byte ReadByte(System::Object ^ ptr, int ofs);
[System.Obsolete("ReadByte(Object, Int32) may be unavailable in future releases.")]
[System.Security.SecurityCritical]
public static byte ReadByte (object ptr, int ofs);
[System.Obsolete("ReadByte(Object, Int32) may be unavailable in future releases.")]
public static byte ReadByte (object ptr, int ofs);
public static byte ReadByte (object ptr, int ofs);
[System.Security.SecurityCritical]
public static byte ReadByte (object ptr, int ofs);
static member ReadByte : obj * int -> byte
Public Shared Function ReadByte (ptr As Object, ofs As Integer) As Byte

Parameters

ptr
Object

非托管内存中源对象的基址。The base address in unmanaged memory of the source object.

ofs
Int32

额外的字节偏移量,在读取前添加到 ptr 参数中。An additional byte offset, which is added to the ptr parameter before reading.

Returns

Byte

从非托管内存按给定的偏移量读取的字节。The byte read from unmanaged memory at the given offset.

Attributes

Exceptions

基址 (ptr) 加上偏移字节 (ofs) 可产生空或无效地址。Base address (ptr) plus offset byte (ofs) produces a null or invalid address.

ptrArrayWithOffset 对象。ptr is an ArrayWithOffset object. 此方法不接受 ArrayWithOffset 参数。This method does not accept ArrayWithOffset parameters.

Remarks

ReadByte 实现与非托管 C 样式字节数组的直接交互,消除将整个非托管数组(使用 Marshal.Copy)复制到单独托管数组的开销,然后再读取其元素值。ReadByte enables direct interaction with an unmanaged C-style byte array, eliminating the expense of copying an entire unmanaged array (using Marshal.Copy) to a separate managed array before reading its element values.

支持从未对齐的内存位置进行读取。Reading from unaligned memory locations is supported.

See also

ReadByte(IntPtr)

从非托管内存读取单个字节。Reads a single byte from unmanaged memory.

public:
 static System::Byte ReadByte(IntPtr ptr);
[System.Security.SecurityCritical]
public static byte ReadByte (IntPtr ptr);
public static byte ReadByte (IntPtr ptr);
static member ReadByte : nativeint -> byte
Public Shared Function ReadByte (ptr As IntPtr) As Byte

Parameters

ptr
IntPtr

非托管内存中开始读取的地址。The address in unmanaged memory from which to read.

Returns

Byte

从非托管内存读取的字节。The byte read from unmanaged memory.

Attributes

Exceptions

ptr 不是识别的格式。ptr is not a recognized format.

- 或 --or- ptrnullptr is null.

- 或 --or- ptr 无效。ptr is invalid.

Examples

下面的示例创建非托管内存块,将字节写入非托管内存,从非托管内存读取字节,然后释放非托管内存。The following example creates a block of unmanaged memory, writes a byte to the unmanaged memory, reads the byte back from unmanaged memory, and then disposes the unmanaged memory.

using System;
using System.Runtime.InteropServices;

 class Example
 {
     static void Main(string[] args)
     {
          // Allocate 1 byte of unmanaged memory.
          IntPtr hGlobal = Marshal.AllocHGlobal(1);

          // Create a new byte.
          byte b = 1;
          Console.WriteLine("Byte written to unmanaged memory: " + b);

          // Write the byte to unmanaged memory.
          Marshal.WriteByte(hGlobal, b);

          // Read byte from unmanaged memory.
          byte c = Marshal.ReadByte(hGlobal);
          Console.WriteLine("Byte read from unmanaged memory: " + c);

          // Free the unmanaged memory.
          Marshal.FreeHGlobal(hGlobal);
          Console.WriteLine("Unmanaged memory was disposed.");
     }
}
Imports System.Runtime.InteropServices

Module Example
    Sub Main()
         ' Allocate 1 byte of unmanaged memory.
         Dim hGlobal As IntPtr = Marshal.AllocHGlobal(1)
         
         ' Create a new byte.
         Dim b As Byte = 1
         
         Console.WriteLine("Byte written to unmanaged memory: {0}", b)
         
         ' Write the byte to unmanaged memory.
         Marshal.WriteByte(hGlobal, b)
         
         ' Read byte from unmanaged memory.
         Dim c As Byte = Marshal.ReadByte(hGlobal)
         Console.WriteLine("Byte read from unmanaged memory: {0}", c)
         
         ' Free the unmanaged memory.
         Marshal.FreeHGlobal(hGlobal)
         Console.WriteLine("Unmanaged memory was disposed.")
    End Sub
End Module

下面的示例演示如何使用 ReadByte 方法读取非托管字符的值。The following example demonstrates how to use the ReadByte method to read the value of an unmanaged character.


using namespace System;
using namespace System::Runtime::InteropServices;



void main()
{
    // Create an unmanaged byte.
    const char * myString = "b";

    // Read the c string as a managed byte.
        Byte ^ myManagedByte = Marshal::ReadByte((IntPtr) (char *) myString);

    // Display the byte to the console.
    Console::WriteLine(myManagedByte);
}

Remarks

ReadByte 的隐含偏移量为0。ReadByte has an implied offset of 0. 此方法使您能够与非托管 C 样式字节数组直接交互,从而消除了在读取其元素值之前将整个非托管数组(使用 Marshal.Copy)复制到单独的托管数组的代价。This method enables direct interaction with an unmanaged C-style byte array, eliminating the expense of copying an entire unmanaged array (using Marshal.Copy) to a separate managed array before reading its element values.

支持从未对齐的内存位置进行读取。Reading from unaligned memory locations is supported.

See also

Applies to