Looping input function

Question

Currently, I have a function that loops to gather input for program execution, but I feel that it is a bit lacking, overthought and unoptimized. I would love any input on the process, coding style, or usability of the function.

I feel like the use of while (true) is not really optimized here.

My code uses curses and unistd.h.

// Heart of the display of the program
void startEvolutionLoop (Grid* grid, size_t speed) {
 clear();
 // Infinitely loops until 'q' is pressed
 while (true) {
 // First of all displays the grid with supporting information
 displayGrid(grid);
 printw("[Space] Evolve once [Enter] Run evolutions [q] Exit\n");
 // Gets the most recently touched character
 int c = getch();
 // - if space (' ') evolves and loops again
 // - if ('q') ends the loops
 // - if enter ('\n') starts a sub-loop similar to the main one, but waits for any character to stop
 if (c == ' ') {
 grid->evolve();
 } else if (c == 'q') {
 return;
 } else if (c == '\n') {
 nodelay(stdscr, TRUE); // Getting of the input is asyncronous
 // Infinitely loops until any key is pressed
 while (true) {
 grid->evolve();
 displayGrid(grid);
 printw("Press any key to end execution... \n"); // Extra whitespace to override previously written stuff in this area
 // If there has been something inputted, then break out of this sub-loop
 if (getch() != ERR) {
 break;
 }
 usleep((__useconds_t)speed * 1000); // Sleep the desired amount of time (in micro seconds converted to milliseconds)
 }
 }
 }
}

For context (which is not necessary), you can check out my GitHub Repo.

• pacmaninbw: What exactly do you want to optimize in the loop, speed or memory usage?

Answer 1

Consider following the Single Responsibility Principal and break the function up into smaller functions that do less.

Note: This answer makes use of the loopEvos() that is provided in the updated version of the source files on GitHub.

void loopEvos (Grid* grid, size_t speed) {
 nodelay(stdscr, TRUE); // Getting of the input is asyncronous
 // Infinitely loops until any key is pressed
 while (true) {
 grid->evolve();
 displayGrid(grid);
 printw("Press any key to end execution...\n");
 // If there has been something inputted, then break out of this sub-loop
 if (getch() != ERR) {
 break;
 }
 usleep((__useconds_t)speed * 1000); // Sleep the desired amount of time (in micro seconds converted to milliseconds)
 }
}

Whenever code is written future expansion of the program/function must be considered. In the function above there is the code :

 if (c == ' ') {
 grid->evolve();
 } else if (c == 'q') {
 return;
 } else if (c == '\n') {
 loopEvos(grid, speed);
 nodelay(stdscr, FALSE);
 }

It would be is easier to expand the code if another type of control statement was used instead. If the code was

 switch (c) {
 case ' ':
 grid->evolve();
 continue;
 case 'q':
 return;
 case '\n':
 loopEvos(grid, speed);
 nodelay(stdscr, FALSE);
 continue:
 default :
 printw("Invalid character input\n");
 return;
 }

It would be easier to handle any additional input characters such as KEY_UP, KEY_LEFT, KEY_DOWN and KEY_UP.

 switch (c) {
 case ' ':
 grid->evolve();
 continue;
 case 'q':
 return;
 case '\n':
 loopEvos(grid, speed);
 nodelay(stdscr, FALSE);
 continue;
 // The following code is modified from procs/procs.hpp in the GitHub account.
 case 's':
 askFileSave(grid);
 continue;
 case 'c':
 changeSettings(&speed);
 continue;
 case KEY_UP:
 if (cursorPosY >= 1) {
 cursorPosY -= 1;
 }
 continue;
 case KEY_LEFT:
 if (cursorPosX >= 2) {
 cursorPosX -= 2;
 }
 continue;
 case KEY_DOWN:
 if (cursorPosY < (grid->y - 1)) {
 cursorPosY += 1;
 }
 continue;
 case KEY_RIGHT:
 if ((cursorPosX / 2) < grid->x - 1) {
 cursorPosX += 2;
 }
 continue;
 default :
 printw("Invalid character input\n");
 return;
 }

It might be easier to read, understand and modify the outer loop if it was a do while loop rather than a while true loop

void startEvolutionLoop (Grid* grid, size_t speed) {
 clear();
 int userInput;
 do {
 // First of all displays the grid with supporting information
 displayGrid(grid);
 printw("[Space] Evolve once [Enter] Run evolutions [q] Exit\n");
 // Gets the most recently touched character
 userInput = getch();
 if (userInput == ' ') {
 grid->evolve();
 } else if (userInput == 'q') {
 continue;
 } else if (userInput == '\n') {
 loopEvos(grid, speed); // from procs/procs.hpp in the GitHub account.
 nodelay(stdscr, FALSE);
 }
 } while (userInput != `q`);
}

• Ziyad Edher: Thank you for the response! The project was mostly a learning demo, but I'll be sure to take your notes into consideration for the future.