Handling/Sowing history

I want to make a program that should show the history of commands like shells do using curves.

My problem is that i don't know how to clear and re-write another command in the same position without print one more prompt.

ex :

Quote:

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myshell > command1

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By pressing the up-curve i want to do

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myshell > command2

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And not print and the last command like

Quote:

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myshell > command1
myshell > command2

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In reality i want to clear and write without clearing the whole screen.

Is this easy or better use something else ?

This sort of terminal manupulation is non-portable. You could try to use the GNU readline library, which is meant for the exact task. Or you could roll something yourself using ncurses. The least preferable option would be hard coded terminal escapes.

It's for linux.
Yes i know it's hard, probably i'll let it go for now.
I suppose that i would use something like gotoxy in order to re-write command.

Thanks

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Originally Posted by ch4

It's for linux.
Yes i know it's hard, probably i'll let it go for now.
I suppose that i would use something like gotoxy in order to re-write command.

Thanks

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GNU doesn't mean Linux. GNU software is intended to be as widely portable as possible. Here's a Windows version of readline.

Readline for Windows

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Originally Posted by ch4

It's for linux.

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Well, you are in luck since the shell does this using the readline() library.

However, I've added a line history to a GUI before. It's fairly simple; you just have a function with a static array to hold the history and a static count as a current place holder. Of course, the GUI provides some features here -- have a look into ncurses(), it is simpler than a GUI API but you can get pretty nice stuff out of it. Certainly a line history will be easy; I *think* there might even be functions built in...

Tab completion, that would be hard.

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Originally Posted by MK27

Tab completion, that would be hard.

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GNU readline has tab-completion built in. You just need to provide a callback which takes a prefix and expands it into a list of possible options. readline takes care of the rest.

Whilst readline and ncurses are both excellent solutions to the problem, there is a simpler solution (with some restrictions, however):
Just print a carriage return ('\r'), and the cursor moves to the beginning of the line. Once that has happened, you can just re-print the line with the new content, and sufficient spaces plus backspaces to delete any remnants of the old line (if the old line was LONGER than the new one). So the output would look something like this:

Code:

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prompt> command 1
\r
prompt> cmd 2      \b\b\b\b\b

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This is fairly portable, but it will not work EVERYWHERE.

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Mats