FileSetPos: Difference between revisions

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(New page: number fileSetPos ( file, number offset ) Sets the current read/write position in the file. Offset is number of bytes from beginning of file. Returns where the offset was actually set at....)
 
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number fileSetPos ( file, number offset )
__NOTOC__
{{Server function}}


Sets the current read/write position in the file. Offset is number of bytes from beginning of file. Returns where the offset was actually set at. Ie if it was above end of file, it will be set at the end of the file.
Sets the current read/write position in the file.
 
==Syntax==
<syntaxhighlight lang="lua">
int fileSetPos ( file theFile, int offset )
</syntaxhighlight>
 
===Required Arguments===
*'''theFile:''' The file handle of which you want to change the read/write position.
*'''offset:''' The new position. This is the number of bytes from the beginning of the file.
 
===Returns===
Returns where the offset was actually set at. I.e. if '''offset''' was past the end of the file, it will be set at the end of the file, and this position will be returned. Returns ''false'' in case of failure (e.g. the specified file handle is invalid).
 
==Example==
This example opens a binary file and prints the value of the byte at position 8 to the console.
<syntaxhighlight lang="lua">
local hFile = fileOpen("test.dat")          -- attempt to open the file
if hFile then                              -- check if it succeeded
    fileSetPos(hFile, 8)                    -- set the read/write position
    local readByte = fileRead(hFile, 1)    -- read one byte from this position
    outputConsole("Byte at position 8 = " .. string.byte(readByte))    -- output it
    fileClose(hFile)                        -- close the file
else
    outputConsole("Unable to open file.dat")
end
</syntaxhighlight>
 
==See Also==
{{File functions}}

Revision as of 10:54, 24 November 2007

Sets the current read/write position in the file.

Syntax

int fileSetPos ( file theFile, int offset )

Required Arguments

  • theFile: The file handle of which you want to change the read/write position.
  • offset: The new position. This is the number of bytes from the beginning of the file.

Returns

Returns where the offset was actually set at. I.e. if offset was past the end of the file, it will be set at the end of the file, and this position will be returned. Returns false in case of failure (e.g. the specified file handle is invalid).

Example

This example opens a binary file and prints the value of the byte at position 8 to the console.

local hFile = fileOpen("test.dat")          -- attempt to open the file
if hFile then                               -- check if it succeeded
    fileSetPos(hFile, 8)                    -- set the read/write position
    local readByte = fileRead(hFile, 1)     -- read one byte from this position
    outputConsole("Byte at position 8 = " .. string.byte(readByte))     -- output it
    fileClose(hFile)                        -- close the file
else
    outputConsole("Unable to open file.dat")
end

See Also