How to avoid rewriting the pieces of text that don't change

Question

I have developed a simple NCurses application that I use for debugging purposes. It constantly prints and updates some variables and their values on a terminal window.

I'm using the printw function to print the variable names and their values like this:

while( ... )
{
    clear();

    printw("var_1: %d\n", var_1);
    printw("var_2: %d\n", var_2);
    printw("var_3: %d\n", var_3);
    ...

    refresh();
}

This produces an output like this:

var_1: 10
var_2: 20
var_3: 30
...

Since this piece of code is inside a loop, I'm constantly rewriting the entire screen, both the variable names and their values.

Notice that the only data that needs to be updated are the values, as the variable names are always the same, so there's no need to re-write them over and over on every iteration.

How can I to avoid rewriting the pieces of text that don't change in my NCurses application?

Tip: Don't have heaps of unrelated variables. Instead create *arrays you can iterate over*. If you can't avoid the variable thing, you can always create a struct with `char*` labels and pointers to the values themselves if they're all of similar types. — tadman, Jan 20 '19 at 20:48

score 2 · Accepted Answer · edited Jan 21 '19 at 11:45

With NCurses, your screen area is just a two dimensional grid. You can print at any position of the screen with mvprintw()

So first print the fixed text a a given position, then, in your loop, print the value at the corresponding value position:

mvprintw( x, y,   "var_1:" );
mvprintw( x, y+1, "var_2:" );
while( ... )
{
/// compute values
   mvprintw( x+6, y,   value1 );
   mvprintw( x+6, y+1, value2 );
}

Reference

How to avoid rewriting the pieces of text that don't change

1 Answers1