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mseek Scilab Group Scilab Function mseek
NAME
mseek - set current position in binary file.
CALLING SEQUENCE
mseek(n [,fd, flag])
PARAMETERS
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.
EXAMPLE
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, meof, mfprintf, fprintfMat, mfscanf, fscanfMat, mget, mgetstr,
mopen, mprintf, mput, mputstr, mscanf, mseek, mtell
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