Since I've been having trouble with it and there doesn't seem to be any examples using the Allegro 5 API, I thought I would ask here: is there a tidy way to implement a function that alters a character string in real-time?

Allegro timing is a pain, and I'm trying to display a character string on the screen in real-time as it's being edited through keyboard input. Any help would be appreciated.

What exactly does ex_font_justify do? It couldn't possibly do all of what I'm asking by itself.

You can either use one of the GUI libraries on the Depot (I'm not sure if any of them supports A5 yet though), or you can whip up your own text entry function. A simple one would, in pseudocode, look something like this:

string read_user_input(string initial = "") {
	// Set the current string buffer to the initial value
	string str = initial;

	// Loop until the user presses Esc or Enter
	do {
		int k = readkey();
		switch (k) {
			// a few special keys:
			// Esc cancels
			case Escape: return initial;
			
			// Return commits
			case Return: return str;

			// Backspace deletes last character
			case Backspace:
				if (str.length > 0)
					str.remove_last_char();
				break;

			// Any other key gets appended to the buffer...
			default:
				// but only if it's a regular key
				if (!is_special_key(k))
					str += key_to_ascii(k);
				break;
		}
		// After each keypress, update the display
		display_the_string(str);
	} while (1);
}

This is a very simple example, you'll need to flesh it out a lot more to get the functionality of a typical textbox, but you get the idea. One of the first steps after getting this one working, you might want to add a cursor position, and instead of manipulating the end of the string only, you'd insert and delete at the cursor position, and display a cursor in the textbox.

Is there a version of keycode_to_ascii in Allegro 5? If not, this will get messy fast. Anyway, I can't seem to shorten the string with backspace. The closest I can get is inserting a space in the string, but then I get a bunch of spaces tacked onto the end. Is there a simpler way to implement a backspace feature?

Oh, I forgot to mention: I have no idea what nihgui.cpp is and can't find it anywhere. So yeah.

examples/nihgui.cpp

The thing is, I need to draw the text to the screen in a very specific way. I just need a function that returns a string, nothing more.

You can also do something like this:

I'm using Unicode but you can change that.

It's very simple.

BTW can you download the example .exe (attached) and check if the beeps sounds on your machine?

Set the currently last character to '\0'

You can always write a 0 at the end. There's a bunch of good stuff here:
http://www.cplusplus.com/reference/clibrary/cstring/

Of course there's no implicit conversion. It's the same as trying to use a C++ string when a C string is expected. That doesn't mean there isn't a way to convert from one form to the other. Use this.

It has nothing to do with Allegro. The only way to reduce the length of C strings is to move the position of the terminator. Perhaps you should ask questions about the basics since it appears you don't know them.

edit: Here's a working example

#include <stdio.h>
#include <string.h>

int main() {

    char example[] = "Hello World!";
    example[strlen(example) - 1] = '\0';

    printf("%s\n", example);

    return 0;
}

It prints "Hello World". Note the removal of the !.

No, I wasn't asking you to write my code for me. You gave suggestions, they didn't work. I accept that I may have misunderstood what you were suggesting, so I wanted to see your implementation in case you meant something different than I thought you did.

Never assume someone's just asking you to write their code for them. Most people want help with their code, not a codesitter.

My original question was whether there was an efficient way to do this with Allegro timing, but I guess there isn't. I can figure it out on my own from here, I think. Unless someone has another suggestion.

I think the same... I can't understand you. "an efficient way to do this with Allegro timing" .

You're talking about separating the Keyboard inputs from the drawing?