mseek

set current position in binary file.

Calling Sequence

mseek(n [,fd, flag])

Arguments

n a positive scalar:  The offset from origin in number of bytes.

: :fd scalar. The fd parameter returned by the function mopen. -1

stands for last opened file. Default value is -1.

: :flag a string. specifies the origin. Default value ‘set’. :

Description

The function mseek() sets the position of the next input or output operation on the stream fd. The new position is at the signed distance given by n bytes from the beginning, from the current position, or from the end of the file, according to the flag value which can be ‘set’, ‘cur’ or ‘end’.

mseek() allows the file position indicator to be set beyond the end of the existing data in the file. If data is later written at this point, subsequent reads of data in the gap will return zero until data is actually written into the gap. mseek(), by itself, does not extend the size of the file.

Examples

file3='test3.bin'
fd1= `mopen`_(file3,'wb');
for i=1:10, `mput`_(i,'d'); end
mseek(0);
`mput`_(678,'d');
mseek(0,fd1,'end');
`mput`_(932,'d');
`mclose`_(fd1)
fd1= `mopen`_(file3,'rb');
res=`mget`_(11,'d')
res1=[1:11]; res1(1)=678;res1($)=932;
if res1<>res ;`write`_(%io(2),'Bug');end;
mseek(0,fd1,'set');

// trying to read more than stored data
res1=`mget`_(100,'d',fd1);
if res1<>res ;`write`_(%io(2),'Bug');end;
`meof`_(fd1)
`mclearerr`_(fd1)
`mclose`_(fd1);

See Also

• mclose closes an opened file
• meof check if end of file has been reached
• mfprintf converts, formats, and writes data to a file
• fprintfMat writes a matrix in a file
• mfscanf reads input from the stream pointer stream (interface to the C fscanf function)
• fscanfMat reads a matrix from a text file
• mget reads byte or word in a given binary format and converts to a double type
• mgetstr reads a character string from a file
• mopen open a file in Scilab
• mprintf converts, formats, and writes data to the main scilab window
• mput writes byte or word in a given binary format
• mputstr write a character string in a file
• mscanf
• mseek set current position in binary file.
• mtell binary file management
• mdelete deletes file(s)