mseek

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
• meof
• mfprintf
• fprintfMat
• mfscanf
• fscanfMat
• mget
• mgetstr
• mopen
• mprintf
• mput
• mputstr
• mscanf
• mseek
• mtell
• mdelete