Switch statements??

[aspand]

Hi,
Can I use an if else statement withing a Case??
e.g Case 'C': if(*roundHr < 3)
.
.
.
.
.
etc
how could I implement that??
Thanks
A

[Hammer]

switch (c)
{
	case 'A':
		if (something == TRUE)
		{
			printf("blurb\n");
		}
		else
		{
			printf("No blurb\n");
		}
		break;
	case 'B':
	 .....
	default:
	 .....
}

Don't put too much inside one case though, your program will get confusing.

[Shadow]

#include <stdio.h>
#include <conio.h>

int choices ( void );

int main ( void )
{
        int Number = 100;
        char Choice;
        while( choices() == 0 )
        {
                Choice=getch();
                switch(Choice)
                {
                        case 'n':
                        if(Number == 100)
                        {
                                printf("%d\n\n", Number);
                        }
                        else
                        {
                                printf("You changed Number's value!\n\n");
                        }
                        break;
                
                        case 27:
                        exit(0);
                        break;
                        
                        default:
                        break;
                }
        }
        return 0;
}

int choices ( void )
{
        printf("N = show number\nEscape = exit\n\n");
        return 0;
}

[Shadow]

> Don't put too much inside one case though, your program will get confusing.
I agree.
Functions! functions! functions!

[Frankiepoon]

Use more function and pointer!!I think it is very important for the speed o fprogram....

[billholm]

People I don't quite get what you mean by function pointers.

Well, I do use a switch statement like this:

/*Start sample*/

void first(void);
void second(void);
void third(void);

...

switch(choice) {
case '1': first(); break;
case '2': second(); break;
case '3': third(); break;
default: break;
}

/*End Sample*/

I don't expand processes inside switch statements.

So what do you think about this style?

[Fordy]

Originally posted by billholm
People I don't quite get what you mean by function pointers.

Dont know if he actually meant function pointers........but you could do something like...

#include <stdio.h>
void first(void){printf("First\n");}
void second(void){printf("Second\n");}
void third(void){printf("Third\n");}
typedef void (*MYFUNC)(void);

int main(int argc, char *argv[])
{
  MYFUNC MyFunc = NULL;
  int x = 0;

  while(x!=4){
  printf("Enter 1,2 or 3 (4 to end)\n");

  scanf("%d",&x);

  if(x == 4)break;

  switch(x){
  case 1:
       MyFunc = (MYFUNC)first;
       break;
  case 2:
       MyFunc = (MYFUNC)second;
       break;
  case 3:
       MyFunc = (MYFUNC)third;
       break;
  }

  MyFunc();
  }
  return 0;
}

[Monster]

Just for fun......

#include <stdio.h>

void first(void){printf("First\n");}
void second(void){printf("Second\n");}
void third(void){printf("Third\n");}
void (*func[])(void) = { first, second, third };

int main(int argc, char *argv[])
{
  int x = 0;

  while(x!=4)
  {
    printf("Enter 1,2 or 3 (4 to end)\n");
    scanf("%d",&x);
    if(x == 4) break;
    if(x > 0 && x < 4) func[x-1]();
  }
  return 0;
}

[billholm]

Well I didn't know that there are other techniques like those... till today that is.

I think I'll practice using those. It could actually shorten some of the codes i have already written.

[Hammer]

In my contest entry, I did a menu based on function pointers, similar to Monsters version, but slightly more dynamic (It worked out the number of items in the menu by itself).

Here's a section of the code that made it work:

struct menu_item
{
	char	*Text;
	void 	(*fptr) (void *);
	void 	*args;
};

static struct menu_item Page2Menu[] =
{
	{ "Search By Chosen Field", ui_DisplayMenu, SearchByFieldMenu },
	{ "Display All Entries", ui_DisplayAll, NULL },
	{ "Set Sort Order", ui_DisplayMenu, SortByFieldMenu },
	{ "Undelete An Entry", ui_UndeleteEntry, NULL },
	{ "Save Changes", ui_Save, NULL },
	{ "Purge Entries Marked For Deletion", ui_PurgeDeleted, NULL },
	{ "Application Options", ui_DisplayMenu, OptionsMenu },
	{ NULL, NULL, NULL }
};

struct menu_item MainMenu[] =
{
	{ "Add New Entry", ui_AddNewEntry, NULL },
	{ "Delete Entry", ui_DeleteEntry, NULL },
	{ "Update Entry", ui_UpdateEntry, NULL },
	{ "Display Entry", ui_SearchAll, (void *)RECF_ID},
	{ "Search By Name", ui_SearchAll, (void *)RECF_NAME },
	{ "Save Changes", ui_Save, NULL },
	{ "More Options", ui_DisplayMenu, Page2Menu },
	{ "Help/About", ui_ShowInfo, NULL },
	{ NULL, NULL, NULL }
};

void ui_DisplayMenu(void *pmenu)
{
	int i, choice;
	struct menu_item *menu = pmenu;
	struct menu_item *item;

	for ( ; ; )
	{
		printf ("---> PhoneBook Menu <---\n");
		for (i = 1, item = menu; item->Text != NULL; item++, i++)
		{
			printf("%2d %s\n", i, item->Text);
		}

		printf(" x Exit Menu\nEnter choice >");

		if ((choice = io_GetInt(i-1)) == -1)
			break;
		item = menu + choice - 1;
		if (item->Text == NULL) break;
		(void) (*item->fptr) (item->args);
	}
}

The io_GetInt() function is in another library, but all it does is ask the user for an int between 1 and the value in the parameter you pass. If they entered the letter x, the function would return -1, and we'd break out of the infinite loop in menu.

The full source is in a zip file on the contest thread if you want to look at this in more detail.