file - file management

Calling Sequence

[unit [,err]]=file('open', file-name [,status] [,access [,recl]] [,format])

file(action,unit)

[units [,typ [,nams [,mod [,swap]]]]] = file([unit])

Parameters

• file-name : string, file name of the file to be opened
• status : string, The status of the file to be opened
  • "new" : file must not exist new file (default)
  • "old" : file must already exists.
  • "unknown" : unknown status
  • "scratch" : file is to be deleted at end of session
• access : string, The type of access to the file
  • "sequential" : sequential access (default)
  • "direct" : direct access.
• format : string,
  • "formatted" : for a formatted file (default)
  • "unformatted" : binary record.
• recl : integer,is the size of records in bytes when access="direct"
• unit : integer, logical unit descriptor of the opened file
• units : integer vector, logical unit descriptor of the opened files. Units 1 5 and 6 are reserved by the system for history file , input and output devices.
• typs : Character string vector, type (C or Fortran) of opened files.
• nams : Character string vector, pathnames of opened files.
• mod : file opening mode. Formed by three digits abc
  • Fortran files
    • a : 0 stands for formatted and 1 for unformatted (binary)
    • b 0 stands for sequential acces and 1 for direct access
    • c : 0 stands for "new", 1 for "old", 2 for "scratch" and 3 for "unknown"
  • C files
    • a : is 1 if file has been opened with a "b" (binary) mode
    • b : is 1 if file has been opened with a "+" (updating) mode
    • c : 1 stands for "r" (read), 2 stands for "w" (write) and 3 for "a" (append)
• swap : automatic swap switch. swap=1 if automatic swap is on. swap is always 0 for Fortran files.
• err : integer, error message number (see error), if open fails. If err is omitted an error message is issued.
• action : is one of the following strings:
  • "close" : closes the file(s) given by the logical unit descriptors given in units
  • "rewind" : puts the pointer at beginning of file
  • "backspace" : puts the pointer at beginning of last record.
  • "last" : puts the pointer after last record.

Description

selects a logical unit unit and manages the file file-name .

[unit [,err]]=file('open', file-name [,status] [,access [,recl]][,format]) allows to open a file with specified properties and to get the associated unit number unit . This unit number may be used for further actions on this file or as file descriptor in read , write , readb , writb , save , load function calls.

file(action,unit) allows to close the file , or move the current file pointer .

file() returns the logical unit descriptors of the opened files. So file('close',file() ) closes all user opened files (C or Fortran type).

Examples

u=file('open',TMPDIR+'/foo','unknown')
for k=1:4
  a=rand(1,4)
  write(u,a)
end
file('rewind',u)
x=read(u,2,4)
file('close',u)
//
u1=file('open',TMPDIR+'/foo','unknown')
u2=mopen(TMPDIR+'/foo1','wb')
[units,typs,nams]=file()
file('close',u1);
mclose(u2);
 
  

See Also

save ,   load ,   write ,   read ,   writb ,   readb ,   xgetfile ,   mopen ,   mclose ,