Modern Fs File ReadAt

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File.ReadAt

Reads up to n bytes at an offset without moving the position.

Syntax

File.ReadAt( pos, buf, n )

Notes

• Reads up to n bytes at pos without moving the position, on every platform.
• Past the end it reads 0 bytes. pos < 0 is FS_INVALID_ARGUMENT; a pipe is FS_NOT_SEEKABLE.
• Safe to call from several threads on one File.

Examples

#import "std/fs"
using fs

dim as ustring dir_ = CreateTempDir( "tkdoc" ).Value( )
dim as ustring p = PathJoin( dir_, "f.txt" )
WriteAllText( p, "0123456789" )
dim as File f
f.OpenRead( p )
dim as ubyte b( 0 to 3 )
print f.ReadAt( 6, @b(0), 4 ).Value( ), chr( b(0) )    '' 4 6
print f.Position( ).Value( )    '' 0 -- unmoved
f.Close( )

RemoveDirAll( dir_ )

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Library: Filesystem Library Category: File Streams Documented under: Files