使用 .NET 4.0
使用 dotPeek .NET 反编译器
与 System.BitConverter.ToInt32() 的代码有点混淆:
public static unsafe int ToInt32(byte[] value, int startIndex)
{
if (value == null)
ThrowHelper.ThrowArgumentNullException(ExceptionArgument.value);
if ((long) (uint) startIndex >= (long) value.Length)
ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.startIndex, ExceptionResource.ArgumentOutOfRange_Index);
if (startIndex > value.Length - 4)
ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_ArrayPlusOffTooSmall);
fixed (byte* numPtr = &value[startIndex])
{
if (startIndex % 4 == 0)
return *(int*) numPtr;
if (BitConverter.IsLittleEndian)
return (int) *numPtr | (int) numPtr[1] << 8 | (int) numPtr[2] << 16 | (int) numPtr[3] << 24;
else
return (int) *numPtr << 24 | (int) numPtr[1] << 16 | (int) numPtr[2] << 8 | (int) numPtr[3];
}
}
如何理解这部分代码?:
if (startIndex % 4 == 0)
return *(int*) numPtr;
我的意思是为什么字节数组中的起始位置很重要?