fseek

Moves the file position to a given byte offset.

Category: Data Import and Analysis > Data Import and Export

Syntax

status = fseek(fid, offset, origin)

Description

The next read or write starts at the new position. fseek(fid, 0, 'eof') followed by ftell gives the file size in bytes. Use a negative offset with 'eof' to look at the end of a file, such as the last few characters.

Input arguments

offset

Number of bytes to move; may be negative.

origin

'bof' start of file, 'cof' current position, 'eof' end of file.

Output arguments

status

0 on success, -1 on failure.

Example

File size and the last bytes

fid = fopen('w.txt', 'w'); fprintf(fid, 'alpha beta gamma'); fclose(fid);
fid = fopen('w.txt');
fseek(fid, 0, 'eof');
sz = ftell(fid)
fseek(fid, -5, 'eof');
tail = fread(fid, 5, '*char')'
fseek(fid, 6, 'bof');
word = fread(fid, 4, '*char')'
fclose(fid);

sz = 16
tail = 'gamma'
word = 'beta'

See also

ftell frewind fread fopen