将代码更改为.net 2.0
.net 2.0 似乎不支持字典键的 OrderByDescending ,如何将此代码更改为 .net 2.0
private static Dictionary<byte[], Func<BinaryReader, Size>> imageFormatDecoders = new Dictionary<byte[], Func<BinaryReader, Size>>()
{
{ new byte[]{ 0x42, 0x4D }, DecodeBitmap},
{ new byte[]{ 0x47, 0x49, 0x46, 0x38, 0x37, 0x61 }, DecodeGif },
{ new byte[]{ 0x47, 0x49, 0x46, 0x38, 0x39, 0x61 }, DecodeGif },
{ new byte[]{ 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A }, DecodePng },
{ new byte[]{ 0xff, 0xd8 }, DecodeJfif },
};
public static Size GetDimensions(BinaryReader binaryReader)
{
int maxMagicBytesLength = imageFormatDecoders.Keys.OrderByDescending(x => x.Length).First().Length;
byte[] magicBytes = new byte[maxMagicBytesLength];
for (int i = 0; i < maxMagicBytesLength; i += 1)
{
magicBytes[i] = binaryReader.ReadByte();
foreach (var kvPair in imageFormatDecoders)
{
if (magicBytes.StartsWith(kvPair.Key))
{
return kvPair.Value(binaryReader);
}
}
}
throw new ArgumentException(errorMessage, "binaryReader");
}
It seem that .net 2.0 do not support OrderByDescending for dictionary keys , how can I change this code to .net 2.0
private static Dictionary<byte[], Func<BinaryReader, Size>> imageFormatDecoders = new Dictionary<byte[], Func<BinaryReader, Size>>()
{
{ new byte[]{ 0x42, 0x4D }, DecodeBitmap},
{ new byte[]{ 0x47, 0x49, 0x46, 0x38, 0x37, 0x61 }, DecodeGif },
{ new byte[]{ 0x47, 0x49, 0x46, 0x38, 0x39, 0x61 }, DecodeGif },
{ new byte[]{ 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A }, DecodePng },
{ new byte[]{ 0xff, 0xd8 }, DecodeJfif },
};
public static Size GetDimensions(BinaryReader binaryReader)
{
int maxMagicBytesLength = imageFormatDecoders.Keys.OrderByDescending(x => x.Length).First().Length;
byte[] magicBytes = new byte[maxMagicBytesLength];
for (int i = 0; i < maxMagicBytesLength; i += 1)
{
magicBytes[i] = binaryReader.ReadByte();
foreach (var kvPair in imageFormatDecoders)
{
if (magicBytes.StartsWith(kvPair.Key))
{
return kvPair.Value(binaryReader);
}
}
}
throw new ArgumentException(errorMessage, "binaryReader");
}
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仅获取字典键中最长字节数组的长度。因此,只需迭代 imageFormatDecoders 中的项目并记录最长的值,即类似这样的内容(未经测试):
This line
just gets the length of the longest byte array in the keys of your dictionary. So just iterate through your items in
imageFormatDecoders
and record the longest value, i.e., something like this (untested):.net 3.5 不支持 OrderByDescending 是什么意思?确实如此。顺便问一下,
Max(x => x.Length)
有什么问题吗?What do you mean that .net 3.5 does not support
OrderByDescending
. It does. And by the way what is wrong withMax(x => x.Length)
?在 .Net 3.5 中,这有什么问题?
输出
What's wrong with this, in .Net 3.5?
Output
我怀疑你只是缺乏;
位于代码文件的顶部。不,切换到 .net 2 在这里没有帮助。
I suspect you simply lack;
At the top of the code file. And no, switching to .net 2 won't help here.