Thread: switch syntax

ok so I sort of understand how the switch case works but I cant get the syntax quite right for what I want to do.

Background info-
ok so I have a PIC controller that i am programming in C. I have three inputs A B and C. and an output X

What I want to do-

the Idea is that I want to make a variable (lets pick "n") and asign a number to that variable depending on what button (or imput A-C) is pressed. that number would then switch the case. so if imput A == 0 then n ==1 and if B == 0 then n == 2 etc. then depending on what n equals I want the corrisponding case # to run. then the Case 1 would give the output X a value of 1 and CASE 2 would give the output X a value of 2 etc.

I hope I made myself clear. I am new and would like a little help to get started! thanks for your help!

Originally Posted by Gutiarplyrinak

ok so I sort of understand how the switch case works but I cant get the syntax quite right for what I want to do.

Background info-
ok so I have a PIC controller that i am programming in C. I have three inputs A B and C. and an output X

What I want to do-

the Idea is that I want to make a variable (lets pick "n") and asign a number to that variable depending on what button (or imput A-C) is pressed. that number would then switch the case. so if imput A == 0 then n ==1 and if B == 0 then n == 2 etc. then depending on what n equals I want the corrisponding case # to run. then the Case 1 would give the output X a value of 1 and CASE 2 would give the output X a value of 2 etc.

I hope I made myself clear. I am new and would like a little help to get started! thanks for your help!

Well... you could try something like this...

Code:

switch (n)
  { 
     case 1 : 
        // call procedure for #1 here
        break;
     case 2 :
       // call procedure for #2 here
       break;
     case 3 : 
       // call procedure for #3 here
       break;
     default :
       puts("SimPal Cindy has a boo boo");
    }

I'm not much of a fan of putting actual code into switch statements. It is a lot cleaner and less error prone to use it to call procedures. You'll understand the first time you have to fix a broken switch-case in a Windows message loop...

yah I understand how that part works but I dont understand how to make an if statement or some other statement to change which case I am running

and how would you call procedures?? Again I am pretty new to all of this

Originally Posted by Gutiarplyrinak

yah I understand how that part works but I dont understand how to make an if statement or some other statement to change which case I am running

I'm sorry... what if statement?

Post your code... lets see what you've got so far...

Code:

var testimputs (var){
while (1){
if (PICBbits.RB5 = 0) //if imput A = 0
n==1;
if (PICBbits.RB4 = 0) //if imput B = 0
n==2;
if (PICBbits.RB3 = 0) //if imput C = 0
n==3;
else
n==0
}

var main (var){
switch (n){
case 0 :
    /*code 0 here/*
case 1 :
   /*code 1 here/*
case 2 :
   /*code 2 here/*
case 3 :
   /*code 3 here/*
}
}

Originally Posted by Gutiarplyrinak

[CODE]var testimputs (var){
while (1){
if (PICBbits.RB5 = 0) //if imput A = 0
n==1;
if (PICBbits.RB4 = 0) //if imput B = 0
n==2;
if (PICBbits.RB3 = 0) //if imput C = 0
n==3;
else
n==0
}

You don't need a switch statement here... you already have it... Here's a made up example to give you the idea... Of course you're going to have to develop your own final version...

Code:

void DoB5On(void)
  {  
     Beep(1000);   
     Sleep(1000);  
     Beep(0);         
   }

void DoB4On(void)
   { 
      StartMotor(7,CLOCKWISE) ;
      Sleep(1000);
    }

void DoB3On(void)
   { 
      StopMotor(7);
      Beep(1000);
      Sleep(10)
      Beep(0);
    }

int main(void)
  {
    while (1)
      {
         if (PICBbits.RB5 == 0)
            DoB5On();
         elseif (PICBbits.RB4 == 0)
            DoB4On();
         elseif (PICBbits.RB3 == 0)
            DoB3On();
       }  
     return 0;
  }

Never mind that the function calls are just made up trash... look at how the button presses are handled in main and how the procedure for each is called as a result.

THANK YOU!!! This was what I was trying to do origionally but someone told me it was better to do a switch (programmers like to do their own stuff you know). but I was trying origionally trying to do what you just showed, I just couldnt figure out how. so thank you

Originally Posted by Gutiarplyrinak

THANK YOU!!! This was what I was trying to do origionally but someone told me it was better to do a switch (programmers like to do their own stuff you know). but I was trying origionally trying to do what you just showed, I just couldnt figure out how. so thank you

No worries... the if -- elseif construct is very much like a switch statement anyway, so why not use it?

You may find this link helpful as well...

Cprogramming.com Tutorial: Introduction to C