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- <title>Blitz3D Docs</title>
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- <h1>ReadByte ( filehandle/stream )</h1>
- <h1>Parameters</h1>
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- filehandle/stream = a valid variable set with the OpenFile, ReadFile command, or OpenTCPStream (v1.52+)
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- <h1>Description</h1>
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- Once you've opened a disk file (or stream) for reading, use this command to read a single byte at a time from the file/stream. Note, a byte is an integer that can take the values 0..255 and occupies 8 bits of storage. Since characters are stored as byte values this function can be used to read a file one character at a time. Reading beyond the end of file does not result in an error, but each value read will be zero.
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- Advanced notes
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- The number that is stored by WriteByte is actually the least significant byte of an integer so negative numbers and numbers above 255 will still have a value between 0..255. Unless you understand how 32 bit integers are stored in 2's compliment notation this will seem strange but it is NOT a bug.
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- Streams can only be used in Blitz Basic v1.52 or greater.
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- <h1><a href=../2d_examples/ReadByte.bb>Example</a></h1>
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- ; Reading and writing a file using ReadByte and WriteByte functions
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- ; Initialise some variables for the example
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- Byte1% = 10 ; store 10
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- Byte2% = 100 ; store 100
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- Byte3% = 255 ; store 255 ( the maximum value that can be stored in a Byte)
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- Byte4% = 256 ; try to store 256 this will end up as 0 ( i.e. 256 - 256 = 0 )
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- Byte5% = 257 ; try to store 257 this will end up as 1 ( i.e. 257 - 256 = 1 )
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- Byte6% = -1 ; try to store -1 this will end up as 255 ( i.e. 256 -1 = 255 )
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- Byte7% = -2 ; try to store 256 this will end up as 254 ( i.e. 256 - 2 = 254 )
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- Byte8% = Asc("A") ; Store the ASCII value for the Character "A" ( i.e. 65 )
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- ; Open a file to write to
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- fileout = WriteFile("mydata.dat ")
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- ; Write the information to the file
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- WriteByte( fileout, Byte1 )
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- WriteByte( fileout, Byte2 )
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- WriteByte( fileout, Byte3 )
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- WriteByte( fileout, Byte4 )
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- WriteByte( fileout, Byte5 )
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- WriteByte( fileout, Byte6 )
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- WriteByte( fileout, Byte7 )
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- WriteByte( fileout, Byte8 )
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- ; Close the file
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- CloseFile( fileout )
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- ; Open the file to Read
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- filein = ReadFile("mydata.dat")
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- Read1 = ReadByte( filein )
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- Read2 = ReadByte( filein )
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- Read3 = ReadByte( filein )
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- Read4 = ReadByte( filein )
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- Read5 = ReadByte( filein )
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- Read6 = ReadByte( filein )
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- Read7 = ReadByte( filein )
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- Read8 = ReadByte( filein )
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- ; Close the file once reading is finished
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- CloseFile( filein )
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- Print "Written - Read"
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- Write Byte1 + " - " : Print Read1
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- Write Byte2 + " - " : Print Read2
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- Write Byte3 + " - " : Print Read3
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- Write Byte4 + " - " : Print Read4
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- Write Byte5 + " - " : Print Read5
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- Write Byte6 + " - " : Print Read6
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- Write Byte7 + " - " : Print Read7
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- Write Byte8 + " - " : Print Chr$( Read8 )
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- WaitKey()
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- <a target=_top href=../index.htm>Index</a><br>
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- Click <a href=http://www.blitzbasic.co.nz/b3ddocs/command.php?name=ReadByte&ref=comments target=_blank>here</a> to view the latest version of this page online</body>
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