2D array of strings in C - c

Question

I'm making an application in C that will use text menus. So, I decided to create a global array containing all the menus. As a workaround of an issue I will mention later, the code looks like this:
char* main_menu[]=
{"Refresh rate", "Help", "Default config", NULL};
char* other_stuff[]=
{"Stuff", "More", NULL};
char** screens[]={main_menu, other_stuff};
And I can use those strings like: screens[0][1] meaning first (or rather second, since we count from zero) option in zeroth/first menu.
It works, but it strikes me as quite inelegant that I had to declare those auxilliary arrays (main_menu and other_stuff). I tried to make use of nested brace initialization of arrays, but always the compiler would complain. Also, before you suggest declaring the array as, say, char* screeens[10][5] - there should be no magic numbers, as this is equally inelegant for me.
I tried:
char** screens[]={
{"Refresh rate", "Help", "Default config", NULL},
{"Stuff", "More", NULL}
};
However, the compiler gives me a warning (and rightfully, as accessing elements yields gibberish):
../main.c:96:1: warning: braces around scalar initializer [enabled by default]
{"Refresh rate", "Help", "Default config", NULL},
^
../main.c:96:1: warning: (near initialization for ‘screens[0]’) [enabled by default]
../main.c:96:1: warning: initialization from incompatible pointer type [enabled by default]
../main.c:96:1: warning: (near initialization for ‘screens[0]’) [enabled by default]
../main.c:96:1: warning: excess elements in scalar initializer [enabled by default]
and so on.
If I change the first line to char* screens[][]={, the compiler won't compile the code at all, giving error: error: array type has incomplete element type.
I'm writing in embedded evironment (avr-gcc 4.8.1), where memory is quite scarce, so I don't want to declare arrays bigger than necessary, thus wasting memory. Is there anything I can do, or is this as simple as possible?

Answer 1

Assuming you have C99 or later, you can use 'compound literals' to initialize your array:
#include <stddef.h> // NULL
char **screens2[] =
{
(char *[]){ "Refresh rate", "Help", "Default config", NULL },
(char *[]){ "Stuff", "More", NULL },
};
Or, if you want to be const-correct (a good thing — thanks to M.M and his comment):
char const * const * screens3[] =
{
(char const * const []){ "Refresh rate", "Help", "Default config", NULL },
(char const * const []){ "Stuff", "More", NULL },
};
Compilation (clean — no warnings or errors):
gcc -std=c11 -O3 -g -Wall -Wextra -Werror -pedantic -c 2das.c
(GCC 5.1.0 on Mac OS X 10.10.5)

Answer 2

I'm making an application in C that will use text menus.
You could try something like this:
#include <stdio.h>
#include<unistd.h>
typedef int (*menu)(void);
void clearScreen(int x){
int i=0;
for(;i<x;i++){
printf("\n");
}
}
int exitMenu(void) {
clearScreen(100);
printf("Exiting... Goodbye\n");
sleep(1);
return 0;
}
int mainMenu(void){
clearScreen(100);
printf("\t\t\tMain Manu\n");
return 0;
}
int updateSystem(void) {
clearScreen(100);
printf("System update...\n");
sleep(1);
return 1;
}
int installVlcFromPpa(void) {
clearScreen(100);
printf("Install VLC from PPA \n");
sleep(1);
return 0;
}
int installVlcFromSource(void) {
clearScreen(100);
printf("Install VLC from Source \n");
sleep(1);
return 0;
}
int uninstallVLC(void) {
clearScreen(100);
printf("Uninstall VLC... \n");
sleep(1);
return 1;
}
int chooseOption(int min, int max){
int option,check;
char c;
do{
printf("Choose an Option:\t");
if(scanf("%d%c",&option,&c) == 0 || c != '\n'){
while((check = getchar()) != 0 && check != '\n');
printf("\tThe option has to be between %d and %d\n\n",min,max);
}else if(option < min || option > max){
printf("\tThe option has to be between %d and %d\n\n",min,max);
}else{
break;
}
}while(1);
return option;
}
void showMenu(char *question, char **options, menu *actions, int length) {
int choose = 0;
int repeat = 1;
int i;
menu act;
do {
printf("\n\t %s \n", question);
for(i = 0; i < length; i++) {
printf("%d. %s\n", (i+1), options[i]);
}
choose = chooseOption(1,length);
printf(" \n");
act = actions[choose - 1];
repeat = act();
if(choose == 3){
repeat = 0;
}
}while(repeat == 1);
}
int installVLC(void) {
clearScreen(100);
char *question = "Installing VLC from:";
char *options[10] = {"PPA", "Source", "Back to VLC menu"};
menu actions[3] = {installVlcFromPpa, installVlcFromSource, mainMenu};
showMenu(question, options, actions, 3);
return 1;
}
int meniuVLC(void) {
clearScreen(100);
char *question = "VLC Options";
char *options[10] = {"Install VLC.", "Uninstall VLC.", "Back to Menu."};
menu actions[3] = {installVLC, uninstallVLC, mainMenu};
showMenu(question, options, actions, 3);
return 1;
}
void startMenu(void){
clearScreen(100);
char *question = "Choose a Menu:";
char *options[10] = {"Update system.", "Install VLC", "Quit"};
menu actions[3] = {updateSystem, meniuVLC, exitMenu};
showMenu(question, options, actions, 3);
}
int main(void){
startMenu();
return 0;
}
Choose a Menu:
1. Update system.
2. Install VLC
3. Quit
Choose an Option:

Answer 3

The most elegant way is to declare them as separate variables.
You can also use the first method but utilizing enums/defines, so that you have screens[MAIN_MENU][...] rather that some magic screens[0xcafebabe][...], it is equally acceptable.