| public static ToDouble ( byte value, int startIndex ) : double | ||
| value | byte | |
| startIndex | int | |
| Результат | double | |
public override async Task Decode(EbmlParser parser, bool forceDecode = false)
{
if (Decoded && !forceDecode)
{
return;
}
if (parser == null)
{
throw new ArgumentNullException(nameof(parser));
}
if (parser.DataAccessor == null)
{
throw new InvalidOperationException(
ExceptionsResourceManager.ResourceManager.GetString("InvalidDecodeState", CultureInfo.CurrentCulture));
}
switch (DataSize.DataSize)
{
case 0:
Value = 0;
break;
case 4:
var floatBuffer = new byte[4];
parser.DataAccessor.Position = DataPosition;
await parser.DataAccessor.ReadAsync(floatBuffer, 0, 4).ConfigureAwait(false);
Utility.ConvertEndiannes(floatBuffer);
Value = BitConverter.ToSingle(floatBuffer);
break;
case 8:
var doubleBuffer = new byte[8];
parser.DataAccessor.Position = DataPosition;
await parser.DataAccessor.ReadAsync(doubleBuffer, 0, 8).ConfigureAwait(false);
Utility.ConvertEndiannes(doubleBuffer);
Value = BitConverter.ToDouble(doubleBuffer);
break;
default:
throw new DecodeException("Can not decode a decimal number that is not either 0, 4 or 8 bytes long");
}
Decoded = true;
}
public DataPage(byte[] page)
{
_byteIterator = 0;
Records = new List <Record> {
Capacity = Static.GetRecordsPerPage()
};
UsedSpace = BC.ToInt32(page, _byteIterator);
_byteIterator += sizeof(int);
for (var i = 0; i < UsedSpace; i++)
{
var key = BC.ToUInt32(page, _byteIterator);
_byteIterator += sizeof(uint);
var radius = BC.ToDouble(page, _byteIterator);
_byteIterator += sizeof(double);
var angle = BC.ToInt16(page, _byteIterator);
_byteIterator += sizeof(short);
Records.Add(new Record(key, radius, angle));
}
}
public static double ToDouble(ReadOnlySpan <byte> value) => Converter.ToDouble(value);
/// <summary>转为浮点数</summary>
/// <param name="value">待转换对象</param>
/// <param name="defaultValue">默认值。待转换对象无效时使用</param>
/// <returns></returns>
public virtual Double ToDouble(Object value, Double defaultValue)
{
if (value == null || value == DBNull.Value)
{
return(defaultValue);
}
// 特殊处理字符串，也是最常见的
if (value is String str)
{
str = ToDBC(str).Trim();
if (str.IsNullOrEmpty())
{
return(defaultValue);
}
if (Double.TryParse(str, out var n))
{
return(n);
}
return(defaultValue);
}
else if (value is Byte[] buf)
{
if (buf == null || buf.Length < 1)
{
return(defaultValue);
}
switch (buf.Length)
{
case 1:
return(buf[0]);
case 2:
return(BitConverter.ToInt16(buf, 0));
case 3:
return(BitConverter.ToInt32(new Byte[] { buf[0], buf[1], buf[2], 0 }, 0));
case 4:
return(BitConverter.ToInt32(buf, 0));
default:
// 凑够8字节
if (buf.Length < 8)
{
var bts = new Byte[8];
Buffer.BlockCopy(buf, 0, bts, 0, buf.Length);
buf = bts;
}
return(BitConverter.ToDouble(buf, 0));
}
}
try
{
return(Convert.ToDouble(value));
}
catch { return(defaultValue); }
}
/// <summary>
/// 从流中读入一个 <see cref="T:System.Int64"/>
/// </summary>
/// <param name="stream">要读取的流</param>
/// <returns>读取的 <see cref="T:System.Int64"/></returns>
public static double ReadDouble(this Stream stream)
{
return(BitConverter.ToDouble(stream.ReadBuffer(sizeof(double)), 0));
}
