根据MSDN:
http://msdn.microsoft.com/en-gb/library/system.intptr(v=vs.100).aspx
这仅仅是“指针或句柄”的一种表示方式。
我已经阅读了一些关于GC如何处理IntPtr与其他托管类型不同的内容,但我没有找到任何文档或文章说明IntPtr的回收方式有所不同,即一旦IntPtr超出范围,就可以被GC回收。
关于为什么没有使用unsafe关键字,请阅读已接受的答案,特别是更新部分:
unsafe代码对安全代码有任何影响吗?
unsafe已经在IntPtr的实现中指定(请参见下面IntPtr实现中的字段声明),因此使用IntPtr的类不必将其使用标记为unsafe。否则,它会级联到可能在其实现中使用不安全代码的其他类。
除了
unsafe
代码不是
IntPtr
之外,它还包括字段
private unsafe void* m_value;
是
unsafe
的,而且你没有直接使用它。
using System.Globalization;
using System.Runtime;
using System.Runtime.ConstrainedExecution;
using System.Runtime.InteropServices;
using System.Runtime.Serialization;
using System.Security;
namespace System
{
[ComVisible(true)]
[__DynamicallyInvokable]
[Serializable]
public struct IntPtr : ISerializable
{
[SecurityCritical]
private unsafe void* m_value;
public static readonly IntPtr Zero;
[__DynamicallyInvokable]
public static int Size
{
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success), TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries"), __DynamicallyInvokable] get
{
return 4;
}
}
[SecuritySafeCritical]
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
[ReliabilityContract(Consistency.MayCorruptInstance, Cer.MayFail)]
[__DynamicallyInvokable]
public IntPtr(int value)
{
this.m_value = (void*) value;
}
[SecuritySafeCritical]
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
[ReliabilityContract(Consistency.MayCorruptInstance, Cer.MayFail)]
[__DynamicallyInvokable]
public IntPtr(long value)
{
this.m_value = (void*) checked ((int) value);
}
[ReliabilityContract(Consistency.MayCorruptInstance, Cer.MayFail)]
[SecurityCritical]
[CLSCompliant(false)]
[TargetedPatchingOptOut("Performance critical to inline this type of method across NGen image boundaries")]
public IntPtr(void* value)
{
this.m_value = value;
}
[SecurityCritical]
private IntPtr(SerializationInfo info, StreamingContext context)
{
long int64 = info.GetInt64("value");
if (IntPtr.Size == 4 && (int64 > (long) int.MaxValue || int64 < (long) int.MinValue))
throw new ArgumentException(Environment.GetResourceString("Serialization_InvalidPtrValue"));
this.m_value = (void*) int64;
}
[ReliabilityContract(Consistency.MayCorruptInstance, Cer.MayFail)]
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
public static explicit operator IntPtr(int value)
{
return new IntPtr(value);
}
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
[ReliabilityContract(Consistency.MayCorruptInstance, Cer.MayFail)]
public static explicit operator IntPtr(long value)
{
return new IntPtr(value);
}
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
[ReliabilityContract(Consistency.MayCorruptInstance, Cer.MayFail)]
[SecurityCritical]
[CLSCompliant(false)]
public static explicit operator IntPtr(void* value)
{
return new IntPtr(value);
}
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
[SecuritySafeCritical]
[CLSCompliant(false)]
public static explicit operator void*(IntPtr value)
{
return value.ToPointer();
}
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
[SecuritySafeCritical]
public static explicit operator int(IntPtr value)
{
return (int) value.m_value;
}
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
[SecuritySafeCritical]
public static explicit operator long(IntPtr value)
{
return (long) (int) value.m_value;
}
[SecuritySafeCritical]
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
public static bool operator ==(IntPtr value1, IntPtr value2)
{
return value1.m_value == value2.m_value;
}
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
[SecuritySafeCritical]
public static bool operator !=(IntPtr value1, IntPtr value2)
{
return value1.m_value != value2.m_value;
}
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
[ReliabilityContract(Consistency.MayCorruptInstance, Cer.MayFail)]
public static IntPtr operator +(IntPtr pointer, int offset)
{
return new IntPtr(pointer.ToInt32() + offset);
}
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
[ReliabilityContract(Consistency.MayCorruptInstance, Cer.MayFail)]
public static IntPtr operator -(IntPtr pointer, int offset)
{
return new IntPtr(pointer.ToInt32() - offset);
}
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
[SecuritySafeCritical]
internal unsafe bool IsNull()
{
return (IntPtr) this.m_value == IntPtr.Zero;
}
[SecurityCritical]
unsafe void ISerializable.GetObjectData(SerializationInfo info, StreamingContext context)
{
if (info == null)
throw new ArgumentNullException("info");
info.AddValue("value", (long) (int) this.m_value);
}
[SecuritySafeCritical]
[__DynamicallyInvokable]
public override unsafe bool Equals(object obj)
{
if (obj is IntPtr)
return this.m_value == ((IntPtr) obj).m_value;
else
return false;
}
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
[SecuritySafeCritical]
[__DynamicallyInvokable]
public override unsafe int GetHashCode()
{
return (int) this.m_value;
}
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
[SecuritySafeCritical]
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
[__DynamicallyInvokable]
public unsafe int ToInt32()
{
return (int) this.m_value;
}
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
[SecuritySafeCritical]
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
[__DynamicallyInvokable]
public unsafe long ToInt64()
{
return (long) (int) this.m_value;
}
[SecuritySafeCritical]
[__DynamicallyInvokable]
public override unsafe string ToString()
{
return ((int) this.m_value).ToString((IFormatProvider) CultureInfo.InvariantCulture);
}
[SecuritySafeCritical]
[__DynamicallyInvokable]
public unsafe string ToString(string format)
{
return ((int) this.m_value).ToString(format, (IFormatProvider) CultureInfo.InvariantCulture);
}
[ReliabilityContract(Consistency.MayCorruptInstance, Cer.MayFail)]
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
public static IntPtr Add(IntPtr pointer, int offset)
{
return pointer + offset;
}
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
[ReliabilityContract(Consistency.MayCorruptInstance, Cer.MayFail)]
public static IntPtr Subtract(IntPtr pointer, int offset)
{
return pointer - offset;
}
[SecuritySafeCritical]
[CLSCompliant(false)]
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
public unsafe void* ToPointer()
{
return this.m_value;
}
}
}