mvprintw adds an extra zero to numbers < 100 [ C, ncurses ]

[Yes]

When health is 100, it prints 100. But when it's less than 100 it adds an extra 0 to the end (i.e., 990 instead of 99). If I try printing health where it's decremented, it prints correctly. Why would that be?


void printEnemy (void) {
cleanupEnemy ();
if (alive) {
mvprintw (y, x, "x");
mvprintw (y + 1, x + 1, "x");
mvprintw (y + 1, x, "x");
mvprintw (y, x + 1, "x");
}

mvprintw (rows - 1, cols - 20, "Enemy health: %d", health);
}

Thanks!

[odyniec]

You may be overwriting the old value -- are you sure the "0" isn't already there?

Besides, I assume the "health" value can be in the range 0-100, so you could probably display it using a minimum field width of 3, ie.:

"Enemy health: %3d"

[nvteighen]

When health is 100, it prints 100. But when it's less than 100 it adds an extra 0 to the end (i.e., 990 instead of 99). If I try printing health where it's decremented, it prints correctly. Why would that be?


void printEnemy (void) {
cleanupEnemy ();
if (alive) {
mvprintw (y, x, "x");
mvprintw (y + 1, x + 1, "x");
mvprintw (y + 1, x, "x");
mvprintw (y, x + 1, "x");
}

mvprintw (rows - 1, cols - 20, "Enemy health: %d", health);
}

I can deduce 'health' is a global variable, isn't it? (Otherwise, that code wouldn't compile). So, maybe another function is setting 'health' incorrectly and making it misbehaive; that's one of the disadvantages of global variables: they're more difficult to debug.

Probably, a "OOP-like" approach, using C structures would be better. So you package all relevant information into one data type and you can just pass the instances into functions. (I hope you know about data structures; they're the most similar thing to objects we have in C).

[gnusci]

I cannot see the problem, try with this small code an let me know whether you get the same problem or not?



#include <stdlib.h>
#include <curses.h>

int main(void){
int health = 99;

initscr();
mvprintw(5,5,"Enemy health: %i\n", health);
refresh();
getch();
endwin();
return 0;
}

[Yes]

Adding 3 infront of the d worked. I.e., 'mvprintw (rows - 1, cols - 20, "Enemy health: %3d", health);' Why is that?

Thanks.

[geirha]

It's probably because when health is 100, it uses three characters to print the number.

100

Then when health goes down to 99, it will print

990

But you are not overwriting the third character, so the last 0 of 100 remains.
The %3d format, ensures that the number uses 3 spaces no matter how small it is, so it will always overwrite all three characters.

_99

This is just a guess, based on a hunch.

EDIT: And this is basically just what odyniec said earlier, but in color.

[Yes]

OH! Ok, that makes sense. Thanks!