File (internal function)

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File(<file handle>)

The File internal function returns the numeric value that specifies the status of file associated with the File Handle.

-1 File not opened.
0 Operation performed successfully.
10 End of file occurred during input.
11 End of file occurred during output.
20 Transmission error during input.
21 Transmission error during output.

Comments and Examples

Print File(N) will return -1 when the file N is not opened. File(N) can be used to separate input from output errors in file processing, including communications files.

Window Interrogation

Using file with the optional parameters, WINDOW_RECT or USABLE_RECT allows BR to distinguish between window dimensions and the useable area of windows.

file(nn,"WINDOW_RECT | USABLE_RECT", MAT num-arrayname)

The above file() reference redimensions num-arrayname to 4 elements and returns X (horizontal), Y (vertical), Width, and Height in pixels of either the window or usable area rectangle.

Fontsize

Using File with FONTSIZE returns a two element array with the height and width of each fixed character position in pixels (used for positioning and sizing controls). For example:

file(N,"FONTSIZE", MAT num-arrayname)


extended syntax examples
file(101,'WINDOW_RECT',mat x)

returns 4 items in mat x

  • x(1)=left
  • x(2)=top
  • x(3)=width
  • x(4)=height


See Also

For additional information about files, see the following: