Curses

Curses is a way to manipulate terminals mainly for text user interfaces in applications.

ncurses.h

The ncurses.h helper file in C includes a lot of other libraries, as well, which means you don't need to include them, as they may bloat your final compiled program[2]:

• stdio.h
• unctrl.h
• stdarg.h
• stddef.h

Example

This is an example of ncurses, the most common curses library, from Dan Gookin's book[2] in C.

goodbye.c

#include <ncurses.h> // Use the ncurses library

int main(void)
{
  initscr(); // allocates memory for present window which is called stdscr[4]
  addstr("Goodbye, cruel C programming!"); // add string to window
  refresh(); // flushes current window to the screen
  getch();   // waits for user input to exit

  endwin();  // call to end or exit our curses program[5]
  return 0;  // ended program without errors
}

Compiling

$ gcc -lncurses goodbye.c -o goodbye
# -lncurses : the curses linker

Running

$ ./goodbye

Functions

Cursor

• move(row, column) - Move the cursor to the Y,X point.

Printing Text

• printw(str[, arg1, arg2, ...]) - printw is printf for ncurses. Uses standard string formatting.
• addstr(str) - Print the string at the cursor.
• addch(char) - Print the current character at the cursor.

Text Formatting

Styles

• attron(attr[ | attr | ...])/attroff(attr[ | attr | ...]) - Set attributes on/off for the following text.
• attrset(attr[ | attr | ...]) - Set attributes for the following text, resetting all previous attributes.

Colors

• int has_colors() - Returns TRUE if terminal can render colors, and FALSE otherwise, using builtin defs for TRUE and FALSE.
• int start_color() - Allows colors to be used. Returns OK if allowed. Usually used right after initscr.

User Input

• int getch() - Waits for user input and returns the inputted character.
• getnstr(str, int n) - Get user input up to n characters. On newline, stores input character buffer in str.

Display

• clrtoeol() - Clears everything that is on the current line under the cursor[7].
• clear() - Clears the screen.
• curs_set(0) - Make cursor invisible on screen.

References

1. https://en.wikipedia.org/wiki/Curses_%28programming_library%29
2. https://www.goodreads.com/book/show/4460597-programmer-s-guide-to-ncurses
3. https://www.linuxhowtos.org/manpages/3x/ncurses.htm
4. https://www.sbarjatiya.com/notes_wiki/index.php/Using_ncurses_library_with_C
5. https://linux.die.net/man/3/endwin
6. https://manpages.debian.org/testing/ncurses-doc/start_color.3ncurses.en.html
7. https://stackoverflow.com/questions/5072881/how-to-clear-a-specific-line-with-ncurses

Last modified: 202401040446