Marshal.ReadInt32 Marshal.ReadInt32 Marshal.ReadInt32 Marshal.ReadInt32 Method

Definition

Reads a 32-bit signed integer from unmanaged memory. Reading from unaligned memory locations is supported.

Overloads

ReadInt32(IntPtr) ReadInt32(IntPtr) ReadInt32(IntPtr) ReadInt32(IntPtr)

Reads a 32-bit signed integer from unmanaged memory.

ReadInt32(IntPtr, Int32) ReadInt32(IntPtr, Int32) ReadInt32(IntPtr, Int32) ReadInt32(IntPtr, Int32)

Reads a 32-bit signed integer at a given offset from unmanaged memory.

ReadInt32(Object, Int32) ReadInt32(Object, Int32) ReadInt32(Object, Int32) ReadInt32(Object, Int32)

Reads a 32-bit signed integer at a given offset from unmanaged memory.

ReadInt32(IntPtr) ReadInt32(IntPtr) ReadInt32(IntPtr) ReadInt32(IntPtr)

Reads a 32-bit signed integer from unmanaged memory.

public:
 static int ReadInt32(IntPtr ptr);
[System.Security.SecurityCritical]
public static int ReadInt32 (IntPtr ptr);
static member ReadInt32 : nativeint -> int
Public Shared Function ReadInt32 (ptr As IntPtr) As Integer

Parameters

ptr
IntPtr IntPtr IntPtr IntPtr

The address in unmanaged memory from which to read.

Returns

The 32-bit signed integer read from unmanaged memory.

Exceptions

ptr is not a recognized format.

-or-

ptr is null.

-or-

ptr is invalid.

Examples

The following example demonstrates how to read and write to an unmanaged array using the ReadInt32 and WriteInt32 methods.

static void ReadWriteInt32()
{
    // Allocate unmanaged memory. 
    int elementSize = 4;
    IntPtr unmanagedArray = Marshal.AllocHGlobal(10 * elementSize);

    // Set the 10 elements of the C-style unmanagedArray
    for (int i = 0; i < 10; i++)
    {
        Marshal.WriteInt32(unmanagedArray, i * elementSize, ((Int32)(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.ReadInt32(unmanagedArray, i * elementSize));
    }

    Marshal.FreeHGlobal(unmanagedArray);

    Console.WriteLine("Done. Press Enter to continue.");
    Console.ReadLine();
}
Sub ReadWriteInt32()
    ' Allocate unmanaged memory. 
    Dim elementSize As Integer = 4
    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.WriteInt32(unmanagedArray, i * elementSize, CType(i + 1, Int32))
    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.ReadInt32(unmanagedArray, i * elementSize))
    Next i

    Marshal.FreeHGlobal(unmanagedArray)

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

The following example demonstrates how to use the ReadInt32 method to read the value of an unmanaged int variable.

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



void main()
{
	// Create an unmanaged integer.
	int myVal = 42;

	// Read the int as a managed Int32.
        Int32 ^ myManagedVal = Marshal::ReadInt32((IntPtr) &myVal);

	// Display the value to the console.
	Console::WriteLine(myManagedVal);
}

Remarks

ReadInt32 has an implied offset of 0. This method enables direct interaction with an unmanaged C-style Int32 array, eliminating the expense of copying an entire unmanaged array (using Marshal.Copy) to a separate managed array before reading its element values.

Reading from unaligned memory locations is supported.

Security

SecurityCriticalAttribute
requires full trust for the immediate caller. This member cannot be used by partially trusted or transparent code.

See also

ReadInt32(IntPtr, Int32) ReadInt32(IntPtr, Int32) ReadInt32(IntPtr, Int32) ReadInt32(IntPtr, Int32)

Reads a 32-bit signed integer at a given offset from unmanaged memory.

public:
 static int ReadInt32(IntPtr ptr, int ofs);
[System.Security.SecurityCritical]
public static int ReadInt32 (IntPtr ptr, int ofs);
static member ReadInt32 : nativeint * int -> int
Public Shared Function ReadInt32 (ptr As IntPtr, ofs As Integer) As Integer

Parameters

ptr
IntPtr IntPtr IntPtr IntPtr

The base address in unmanaged memory from which to read.

ofs
Int32 Int32 Int32 Int32

An additional byte offset, which is added to the ptr parameter before reading.

Returns

The 32-bit signed integer read from unmanaged memory.

Exceptions

Base address (ptr) plus offset byte (ofs) produces a null or invalid address.

Examples

The following example demonstrates how to read and write to an unmanaged array using the ReadInt32 and WriteInt32 methods.

static void ReadWriteInt32()
{
    // Allocate unmanaged memory. 
    int elementSize = 4;
    IntPtr unmanagedArray = Marshal.AllocHGlobal(10 * elementSize);

    // Set the 10 elements of the C-style unmanagedArray
    for (int i = 0; i < 10; i++)
    {
        Marshal.WriteInt32(unmanagedArray, i * elementSize, ((Int32)(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.ReadInt32(unmanagedArray, i * elementSize));
    }

    Marshal.FreeHGlobal(unmanagedArray);

    Console.WriteLine("Done. Press Enter to continue.");
    Console.ReadLine();
}
Sub ReadWriteInt32()
    ' Allocate unmanaged memory. 
    Dim elementSize As Integer = 4
    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.WriteInt32(unmanagedArray, i * elementSize, CType(i + 1, Int32))
    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.ReadInt32(unmanagedArray, i * elementSize))
    Next i

    Marshal.FreeHGlobal(unmanagedArray)

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

The following example demonstrates how to use the ReadInt32 method to read the value of an unmanaged int variable.

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



void main()
{
    // Create an unmanaged int pointer.
    int * myVal;
    int tmp = 42;
    // Initialize it to another value.
    myVal = &tmp;

    // Read value as a managed Int32.
    Int32 ^ myManagedVal = Marshal::ReadInt32((IntPtr) myVal, 0);

    // Display the value to the console.
    Console::WriteLine(myManagedVal);
}

Remarks

ReadInt32 enables direct interaction with an unmanaged 32-bit signed array, eliminating the expense of copying an entire unmanaged array (using Marshal.Copy) to a separate managed array before reading its element values.

Reading from unaligned memory locations is supported.

Security

SecurityCriticalAttribute
requires full trust for the immediate caller. This member cannot be used by partially trusted or transparent code.

See also

ReadInt32(Object, Int32) ReadInt32(Object, Int32) ReadInt32(Object, Int32) ReadInt32(Object, Int32)

Warning

This API is now obsolete.

Reads a 32-bit signed integer at a given offset from unmanaged memory.

public:
 static int ReadInt32(System::Object ^ ptr, int ofs);
[System.Obsolete("ReadInt32(Object, Int32) may be unavailable in future releases.")]
[System.Security.SecurityCritical]
public static int ReadInt32 (object ptr, int ofs);
static member ReadInt32 : obj * int -> int
Public Shared Function ReadInt32 (ptr As Object, ofs As Integer) As Integer

Parameters

ptr
Object Object Object Object

The base address in unmanaged memory of the source object.

ofs
Int32 Int32 Int32 Int32

An additional byte offset, which is added to the ptr parameter before reading.

Returns

The 32-bit signed integer read from unmanaged memory at the given offset.

Exceptions

Base address (ptr) plus offset byte (ofs) produces a null or invalid address.

Remarks

ReadInt32 enables direct interaction with an unmanaged 32-bit signed array, eliminating the expense of copying an entire unmanaged array (using Marshal.Copy) to a separate managed array before reading its element values.

Reading from unaligned memory locations is supported.

Security

SecurityCriticalAttribute
requires full trust for the immediate caller. This member cannot be used by partially trusted or transparent code.

See also

Applies to