Find (search) the specified string in stream stream and byte[]

Find (search) the specified string in stream stream and byte[]

Here is a look at two Search extension methods, one is the extension of the stream type, the other is the extension of the byte[] type,

If everyone has a better "algorithm", please give the reply, we optimize together.

--common extension code, need this part of the code support.

Using System;
Using System.Collections.Generic;
Using System.Linq;
Using System.Text;
Using System.IO;
Using System.Drawing;

Namespace IMS.BLL
{
<summary>
Transformation extension method classes between stream, String, byte[]
</summary>
public static Class Streamextend
{
#region Stream Extension
<summary>
Stream stream is converted to a byte array
</summary>
<returns></returns>
public static byte[] Tobytearray (the This stream stream)
{
byte[] bytes = new Byte[stream. Length];
Stream. Read (bytes, 0, bytes. Length);
Sets the current stream's position as the start of the stream
Stream. Seek (0, seekorigin.begin);
return bytes;
}
<summary>
Stream converted to image image
</summary>
<returns></returns>
public static Image Toimage (the This stream stream)
{
Image img = new Bitmap (stream);
return img;
}
<summary>
Stream into string, using Encoding.default encoding
</summary>
<returns></returns>
public static string Tostr (the This stream stream)
{
Return System.Text.Encoding.Default.GetString (stream. Tobytearray ());
}
<summary>
Searches for the specified byte[in the current stream]
</summary>
<param name= "Arr" ></param>
<param name= "key" > Search keyword </param>
<param name= "Beginposition" > Search start position </param>
<returns> returns the first occurrence of byte[in the stream if present, otherwise returns -1</returns>
public static long Search (this stream stream, long beginposition, byte[] key)
{
if (stream = = NULL | | stream. Length <= beginposition)
return-1;

if (key = null | | stream. Length < key. Length)
return-1;

Long I=-1;
Long j =-1;
int currentbyte = Int. MinValue;
For (I=beginposition;i<stream. length;i++)
{
if (stream. Length < key. Length + i)
Break

Stream. Seek (I, seekorigin.begin);
for (j = 0; J < Key. Length; J + +)
{
Currentbyte = stream. ReadByte ();
if (Currentbyte!= key[j])
Break
}
if (j = = key. Length)
return i;

if (Currentbyte = = 1)
Break
}
return-1;
}
#endregion

#region byte[] Extension
<summary>
Byte[] Convert to stream stream
</summary>
<returns></returns>
public static Stream Tostream (this byte[] arr)
{
Stream stream = new MemoryStream (arr);
Sets the position of the current stream as the start of the stream www.2cto.com
Stream. Seek (0, seekorigin.begin);
return stream;
}
<summary>
Byte[] Convert to Image
</summary>
<returns></returns>
public static Image Toimage (this byte[] arr)
{
Return Image.fromstream (arr. Tostream ());
}
<summary>
Convert to string, using Encoding.default encoding
</summary>
<returns></returns>
public static string Tostr (this byte[] arr)
{
return System.Text.Encoding.Default.GetString (arr);
}
<summary>
Search
</summary>
<param name= "Arr" ></param>
<param name= "key" > Search keyword </param>
<param name= "Beginpos" > Search start position </param>
<returns></returns>
public static int Search (this byte[] arr, int beginposition, byte[] key)
{
if (arr = null | | arr. Length <= beginposition)
return-1;

if (key = = NULL | | arr. Length < key. Length)
return-1;

int i =-1;
Int j =-1;
for (i = Beginposition i < arr. Length; i++)
{
if (arr. Length < key. Length + i)
Break

for (j = 0; J < Key. Length; J + +)
{
if (Arr[i+j]!= key[j])
Break
}
if (j = = key. Length)
return i;
}
return-1;
}
#endregion

#region String Extension
<summary>
string conversion to byte[]
</summary>
<returns></returns>
public static byte[] Tobytearray (This string str)
{
return System.Text.Encoding.Default.GetBytes (str);
}
<summary>
String converted to Stream
</summary>
<returns></returns>
public static Stream Tostream (This string str)
{
Stream stream = new MemoryStream (str. Tobytearray ());
Sets the current stream's position as the start of the stream
Stream. Seek (0, seekorigin.begin);
return stream;
}
#endregion
}
}

------------------------

--Test scripts

byte[] arr = "0123456789111". Tobytearray ();
byte[] Key1 = "123". Tobytearray ();
byte[] Key2 = "678". Tobytearray ();
byte[] Key3 = "911". Tobytearray ();
byte[] Key4 = "111". Tobytearray ();
In-stream search test
Stream sm = arr. Tostream ();
Long index1 = Sm. Search (0, Key1);
Long index2 = Sm. Search (0, Key2);
Long index3 = Sm. Search (0, Key3);
Long index4 = Sm. Search (0, Key4);
Byte[] Internal Search test
Long index10 = arr. Search (0, Key1);
Long index20 = arr. Search (0, Key2);
Long index30 = arr. Search (0, Key3);
Long index40 = arr. Search (0, Key4);

-----Excerpt from the Green Studio column





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