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# ropen

`ropen`()
  Syntax:

    `ropen("infile")`

    `ropen()`

  Description:
    `Ropen()` opens infile for reading. A subsequent `ropen()` with no arguments closes the previously opened infile. A file which is re-opened with `ropen(infile)` positions the stream at the beginning of the file.

  Example:

  >     proc r() {
  >        ropen("file.dat")
  >        for (i=0; i<ndat; i=i+1) {
  >           x[i] = fscan()  y[i]=fscan()
  >        }
  >        ropen()
  >     }

  Diagnostics:
    This function returns 0 if the file is not successfully opened.

  See also

  read, `fscan()`, `getstr()`, `File`

  Warning

  There is no way to open more than one read file at a time. The same is true for write files.

`wopen`()
  Syntax:

    `wopen("outfile)`

    `wopen()`

  Description:
    `Wopen` is similar to `ropen` but opens a file for writing. Contents of an already existing outfile are destroyed. Wopened files are written to with `fprint()`. With no argument, the previously wopened file is closed. Wopen returns 0 on failure to open a file.

  Example:

  >     proc w() {
  >        wopen("file.dat")
  >        for (i=0; i<ndat; i=i+1) {
  >           fprint("%g %g\n", x[i], y[i])
  >        }
  >        wopen()
  >     }

  See also

  `fprint()`, `File()`

`xopen`()
  Syntax:

    `xopen("hocfile")`

    `xopen("hocfile", "RCSrevision")`

  Description:
    `Xopen()` executes the commands in `hocfile`. This is a convenient way to define user functions and procedures. An optional second argument is the RCS revision number in the form of a string. The RCS file with that revision number is checked out into a temporary file and executed. The temporary file is then removed. A file of the same primary name is unaffected.

`fprint`()

  Same as `printf()` but prints to a file opened with `wopen()`. If no file is opened it prints to the standard output.

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