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Unbuffered input, input form on VMS.

dave_c asked
Medium Priority
Last Modified: 2020-04-13
Hello, I hope someone can help:

I would like to use an "instant response" menu for a VMS C program that I am writing. I am working on Open VMS AXP 6.1 with Dec C 4.0. The getch() type functions are not available. setvbuf with the unbuffered option does not work either. Every input function (even file I/O directed at stdin) waits for the user to press enter before the program continues. I want it to allow the user to press only one key. I even tried closing stdin and reopening it using "SYS$INPUT" as the file, then using setvbuf, but that did not work either. Unbuffered input works with Cobol programs on this system so I think it should be possible with C.
Also, I would really like to design a nice input form with multiple fields that would allow the user to use the arrow or tab keys to move between fields. Does anyone know of any nice headers or libraries to allow me to do this?

Any suggestions will be greatly appreciated - even if it is to tell me that it cannot be done. (or at least is not worth it for a small program) Thank you very much.

I am a student, and I need this information for a college project that I am working on. None of the CIS Professors currently know how to do this, however, they all would like to know. So, if you know the answer, it will get a LOT of use by many future students I am sure. Thanks again.

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I'm sorry if this is a poor answer, but you will have to use a "qiow" call. I have forgot the parameters, as the have removed the only VMS system I had access to long ago... If I where you, I'd check with my system administrator.
I'm afraid it is not worth a small program.

This said, you need the curses library to do what you want.
Have a look at curses(3) man page:

"The Curses package allows: overall screen, window, and pad manipulation; output to windows and pads; reading terminal input; control over terminal and Curses input and output options; environment query routines; color manipulation; use of soft label keys; terminfo database access; and access to low-level Curses routines."

BTW, you have no chance to read a single character with stdio library.

HTH, julio

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