Can I use a case inside another case in a Switch Case in C

Question

Here, In the Switch Case I am using some key events.

When I press 0 it directs to Case 0: and goes back to the MainWindow I have, by closing the second-one(Window2). And If I press 1 it directs to Case 1 and so on respectively, where the operations will be executed separatedly.

My key events:

    g_printerr("%s\n", gdk_keyval_name (event->keyval));
    keypressed=gdk_keyval_name (event->keyval);
    printf("The KeyEvent is: %s\n", keypressed);     
    char ch[10];
    sprintf(ch, "%s\n", keypressed);   
    printf("The NewKeyEvent is: %s\n", ch);
    int holdch=atoi(ch);

Switch Case:

switch(holdch)
         {
              case 0:
                   printf("Close Window2")
              break;   
              case 1:
                   printf("Open Quadrant1");
              break;
              case 2:
                   printf("Open Quadrant2");
              break;
              case 3:
                   printf("Open Quadrant3");
              break;
              case 4:
                   printf("Open Quadrant4");
              break;
           }

Now, I want to close the operations getting run from Case(1-4) when running and come back to the Second window from where it left before.

How to do this? Can another Cases be used inside Case(1-4)? This time I want to use key-buttons like Esc or q for that. Is it possible?

NOTE:

Case 0-> Close the window where I am now and after this there is no chance of executing other cases. As Second Window is the Window containing 4 Quadrants.

Case(1-4)-> All are executable but can be executed one at a time.

"I want to close the operations getting run from Case(1-4) when running" What does this mean? Do you want to abort the code currently executed, or do you want to return after that code is done executing? — Lundin, Sep 16 '15 at 07:55
I want to abort the code currently executed. Its not I want to return after the ecexution. — djgharphalia07, Sep 16 '15 at 08:30

sergej · Accepted Answer · 2018-08-29T06:26:36.167

4

There can be another switch statement inside a cases (nested switch case statements). Example:

switch(keyevent) {
case 0:
    printf("Close Window2")
    break;   
case 1:
   printf("Open Quadrant1");
   switch(foo) {
   case 1:
       // ...
   }
   break;
   // ...
}

But, if I understand your use-case correctly, I don't think you need it. How bout something like that:

switch(keyevent) {
case 0:
    printf("Close Window2")
    break;   
case 1:
    q1_is_open = true;
    printf("Open Quadrant1");
    break;
case 2:
    q2_is_open = true;
    printf("Open Quadrant2");
    break;
case 3:
    q3_is_open = true;
    printf("Open Quadrant3");
    break;
case 4:
    q4_is_open = true;
    printf("Open Quadrant4");
    break;
case Q_BUTTON_PRESSED:
    if (q1_is_open) {
        printf("Close Quadrant1");
        q1_is_open = false;
    }
    if (q2_is_open) {
        printf("Close Quadrant2");
        q2_is_open = false;
    }
    if (q3_is_open) {
        printf("Close Quadrant3");
        q3_is_open = false;
    }
    if (q4_is_open) {
        printf("Close Quadrant4");
        q4_is_open = false;
    }
    break;
}

edited Aug 29 '18 at 06:26

answered Sep 16 '15 at 08:37

sergej

17,147
6
52
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Awesome :) But my confusion now is can I use Q as a event there? My key values are integer till now. I will edit and take a look I am showing my keyevents. How to take Q as a event so that it goes to **case Q_BUTTON_PRESSED:** – djgharphalia07 Sep 16 '15 at 08:48
1

@djgharphalia07 Instead of Q_BUTTON_PRESSED you can use your integer value or `#define Q_BUTTON_PRESSED 42` – sergej Sep 16 '15 at 08:58
Sure :) I will try and let you know. – djgharphalia07 Sep 16 '15 at 09:01
As far as I know, *If statements* inside *Cases* are not used so much as it takes time to execute. To overcome this Cases are used! Anyway it will be better if I could use another keys other than integers. – djgharphalia07 Sep 16 '15 at 09:41
@djgharphalia07 Cases take also time to execute ;) A switch variable (key) has to be a value that can be expressed as an integer. – sergej Sep 16 '15 at 10:06
Ok :( but it is not taking value as 999 or 99...for veification I printed the key value as you have seen. It is taking only 9. Why? – djgharphalia07 Sep 16 '15 at 10:13
@djgharphalia07 I cant say why without looking at the code. – sergej Sep 16 '15 at 10:15
**#define Q_BUTTON_PRESSED 99** I have just done this. As you suggested. – djgharphalia07 Sep 16 '15 at 10:18
@djgharphalia07 Have you tested with `case 99:` instead of `case Q_BUTTON_PRESSED:` ? – sergej Sep 16 '15 at 10:20
Yes, I did :( Same. I cant close the selected quadrant. – djgharphalia07 Sep 16 '15 at 10:33
If I take Case 9: or Case 5: or anything singular it works... How to send double values. – djgharphalia07 Sep 17 '15 at 06:11
@djgharphalia07 Without looking at the code it would be just guessing. Maybe you should post another question. – sergej Sep 18 '15 at 08:55

score 1 · Answer 2 · edited May 23 '17 at 12:22

1

If you want to run your main-window and quadrant-window code sequentially you'll need to run whatever you have in cases 1-4 in a separate thread:

How do I start threads in plain C?

The code in that thread will have to have a switch which processes the key strokes that you want to use for exiting it.

You can nest switch statements.

(If this doesn't help then you'll need to re-word your question.)

edited May 23 '17 at 12:22

Community

1
1

answered Sep 16 '15 at 08:27

MarkJL

485
1
9
17

1

Your answer is informative too! And you get the reward :) – djgharphalia07 Sep 16 '15 at 10:03

Can I use a case inside another case in a Switch Case in C

2 Answers2