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Fall through case structure


 
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# 1  
Old 07-23-2009
Fall through case structure

Hello Experts,

I was wondering how can we get a fall trough case structure.
Eg: If we have two cases A and B and a default; if I do not break after A, it should execute all the statements of A as well as B if I break after B else fall through even lower.
I tried this:

Code:
#!/bin/sh
v1=1
case ${v1} in
    "1")
        echo "1"
    "0")
        echo "0"
        ;;
    *)
        ;;
esac

The output I get is :
Code:
fallCase.sh[4]: 0403-057 Syntax error at line 7 : `)' is not expected.

I guess the ")" pointed out by the error is the one I have highlighted above in the code; and it's problematic because of the missing ";;" after first case.

Could you please tell me what I should be doing to correct it!

Thank You.

Regards,
HKansal
# 2  
Old 07-24-2009
You answered it yourself - the ;; is missing behind A ie. the check for "1".
For having A true and wanting B executed too, you should just add the execution of B behind A. It is not very well written then but it works. If there are more complex things but "echo 1" or "echo 0", you might want to write these actions as functions above the case construct. So you will only have to call the function names.

Example:
Code:
#!/bin/sh

my_func1()
{
     echo 1
     # and some more things to do in here maybe
     # ...
}

my_func2()
{
     echo 0
     # and some more things to do in here maybe
     # ...
}


v1=1
case ${v1} in
    "1")
        my_func1
        my_func2
        ;;
    "0")
        my_func2
        ;;
    *)
        ;;
esac

exit 0

# 3  
Old 07-24-2009
Hello Zaxxon,

Thank you for confirming that my thought process was correct. Smilie

Let us consider the code you gave, I want to avoid writing "my_func2" twice. Can we do that?

Thank You.

Regards,
HKansal
# 4  
Old 07-24-2009
It's possible...

It's possible to only have one function, but you'd be sending it arguments...and inside that function, you're going to end up re-implementing the exact same thing.

There's no "good" way to do this in bash.
# 5  
Old 07-27-2009
Somewhere you will have to call your 2nd function again. I have no automatical "fall through" as you asked before in mind. At least by just calling it by it's name you have at least less overhead.
# 6  
Old 07-27-2009
Quote:
Originally Posted by hkansal
Hello Experts,

I was wondering how can we get a fall trough case structure.
Eg: If we have two cases A and B and a default; if I do not break after A, it should execute all the statements of A as well as B if I break after B else fall through even lower.
[...]
Some shells (ksh93, zsh and bash4) support what you are asking for:

Code:
ksh-M 93t 2008-11-04$ v=a
ksh-M 93t 2008-11-04$ case $v in a) print a;& b) print b;;esac
a
b

# 7  
Old 08-03-2009
hmmm...

Thanks everyone for the replies. I think I should go with what Zaxxon told me earlier and as I had initially done it. I don't require functions because only single line of code, so that can be put there itself.

Regards,
HKansal

Last edited by hkansal; 08-03-2009 at 03:06 PM.. Reason: spelling mistake
 

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