File opening and closing

<fopen> - Open file.

FOPEN Open file.

FID = FOPEN(FILENAME) opens the file FILENAME for read access.

FILENAME is a string containing the name of the file to be opened.

(On PC systems, FOPEN opens files for binary read access.)

FILENAME can be a MATLABPATH relative partial pathname. If the

file is not found in the current working directory, FOPEN searches for

It on the matlab search path. On unix systems, filename may also start

with a "~/" or a "~username/", which FOPEN expands to the current

user's home directory or the specified user's home directory,

respectively.

FID is a scalar MATLAB integer valued double, called a file identifier.

You use FID as the first argument to other file input/output

routines, such as FREAD and FCLOSE. If FOPEN cannot open the file, it

returns -1.

FID = FOPEN(FILENAME,PERMISSION) opens the file FILENAME in the

mode specified by PERMISSION:

'r' open file for reading

'w' open file for writing; discard existing contents

'a' open or create file for writing; append data to end of file

'r+' open (do not create) file for reading and writing

'w+' open or create file for reading and writing; discard

existing contents

'a+' open or create file for reading and writing; append data

to end of file

'W' open file for writing without automatic flushing

'A' open file for appending without automatic flushing

FILENAME can be a MATLABPATH relative partial pathname only if the file

is opened for reading.

You can open files in binary mode (the default) or in text mode.

In binary mode, no characters get singled out for special treatment.

In text mode on the PC, the carriage return character preceding

a newline character is deleted on input and added before the newline

character on output. To open a file in text mode, append 't' to the

permission string, for example 'rt' and 'w+t'. (On Unix, text and

binary mode are the same, so this has no effect. On PC systems

this is critical.)

If the file is opened in update mode ('+'), you must use an FSEEK or

FREWIND between an input command like FREAD, FSCANF, FGETS, or FGETL

and an output command like FWRITE or FPRINTF. You must also use an

FSEEK or FREWIND between an output command and an input command.

Two file identifiers are automatically available and need not be

opened. They are FID=1 (standard output) and FID=2 (standard error).

[FID, MESSAGE] = FOPEN(FILENAME,...) returns a system dependent error

message if the open is not successful.

[FID, MESSAGE] = FOPEN(FILENAME,PERMISSION,MACHINEFORMAT) opens the

specified file with the specified PERMISSION and treats data read

using FREAD or data written using FWRITE as having a format given

by MACHINEFORMAT. MACHINEFORMAT is one of the following strings:

'native' or 'n' - local machine format - the default

'ieee-le' or 'l' - IEEE floating point with little-endian

byte ordering

'ieee-be' or 'b' - IEEE floating point with big-endian

byte ordering

'ieee-le.l64' or 'a' - IEEE floating point with little-endian

byte ordering and 64 bit long data type

'ieee-be.l64' or 's ' - IEEE floating point with big-endian byte

ordering and 64 bit long data type.

[FID, MESSAGE] = FOPEN(FILENAME,PERMISSION,MACHINEFORMAT,ENCODING)

opens the specified file using the specified PERMISSION and

MACHINEFORMAT. ENCODING is a string that specifies the character

encoding scheme associated with the file. It must be the empty

string ('') or a name or alias for an encoding scheme. Some examples

are 'UTF-8', 'latin1', 'US-ASCII', and 'Shift_JIS'. For common names

and aliases, see the Web site

http://www.iana.org/assignments/character-sets. If ENCODING is

unspecified or is the empty string (''), MATLAB's default encoding

scheme is used.

[FILENAME,PERMISSION,MACHINEFORMAT,ENCODING] = FOPEN(FID) returns the

filename, permission, machine format, and character encoding values

used by MATLAB when it opened the file associated with identifier FID.

MATLAB does not determine these output values by reading information

from the opened file. For any of these parameters that were not

specified when the file was opened, MATLAB returns its default value.

The ENCODING string is a standard character encoding scheme name that

may not be the same as the ENCODING argument used in the call to FOPEN

that opened the file. An invalid FID returns empty strings for all

output arguments.

FIDS = FOPEN('all') returns a row vector containing the file

identifiers for all the files currently opened by the user

(but not 1 or 2).

The 'W' and 'A' permissions do not automatically perform a flush

of the current output buffer after output operations.

See also fclose, ferror, fgetl, fgets, fprintf, fread, fscanf, fseek,

ftell, fwrite.

Overloaded methods:

serial/fopen

icinterface/fopen

Reference page in Help browser

doc fopen

<fclose> - Close file.

FCLOSE Close file.

ST = FCLOSE(FID) closes the file associated with file identifier FID,

which is an integer value obtained from an earlier call to FOPEN.

FCLOSE returns 0 if successful or -1 if not. If FID does not represent

an open file, or if it is equal to 0 (standard input), 1 (standard

output), or 2 (standard error), FCLOSE throws an error.

ST = FCLOSE('all') closes all open files, except 0, 1 and 2.

See also fopen, ferror, fprintf, fread, frewind, fscanf, ftell, fwrite.

Overloaded methods:

serial/fclose

icinterface/fclose

Reference page in Help browser

doc fclose