From: kers AT hplb DOT hpl DOT hp DOT com ()
Newsgroups: comp.os.msdos.djgpp,comp.lang.c
Subject: Re: Recursions and Static declarations....?Is this wrong...
Date: 19 Jul 2002 11:08:36 GMT
Organization: Hewlett-Packard Laboratories, Bristol, UK
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In article <ah8qp0$sdn$1 AT nets3 DOT rz DOT rwth-aachen DOT de>,
	Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de> writes:
> In comp.os.msdos.djgpp kers AT hplb DOT hpl DOT hp DOT com wrote:
>> In article <ah8k0q$lqv$1 AT nets3 DOT rz DOT rwth-aachen DOT de>,
>> 	Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de> writes:
>>> 
>>> No, you can't.  At least not sensibly, in the way you did it.  You
>>> shouldn't be recursing for this, in the first place, nor should you
>>> ever use static variables to keep state across a recursion call.
> 
>> Not even for such things as recording recursion depth for prettyprinting?
> 
> Not in a useful way, if the static is local to the recursive function.

void printIndented( FILE *sink, Tree t )
    {
    static int depth = -1;
    int i;
    depth += 1;
    for (int i = 0; i < depth; i += 1) fputc( ' ', sink );
    if (isLeaf( t ))
	fprintf( sink, "=%s\n", leafString( t ) );
    else
        {
        fprintf( sink, "*%s\n", nodeString( t ) );
        for (int i = 0; i < treeKidCount( t ); i += 1)
            printIndented( sink, treeKid( t, i ) );
        }
    depth -= 1;
    } 

perhaps the example is too simple to raise the point you're addressing?

[It usually turns out in the end, in C anyway, to be easier to pass
the depth in as a parameter. This can make it harder to share interfaces,
which is annoying.]

-- 
Chris "electric hedgehog" Dollin
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