From: Luuk <Luuk@...>
Date: 2011-05-19T02:15:27+09:00
Subject: Re: Linux utility with reverse index facility?

On 18-05-2011 05:40, Robert Nichols wrote:
> On 05/16/2011 05:38 AM, no.top.post@gmail.com wrote:
>> awk&stuff can "give me the the Nth element",
>> but, without writing your own search-loop,
>> what can "give me the index of the 'element'
>> which is<elementValue>" ?
>>
>> I think it's called 'reverse indexing' ?
> 
> In awk, it's just as easy to build an array where your "elementValues"
> are the indices and the values stored in the array are ordinal numbers.
> I,e., instead of
>     myArray[n++] = "cheese"
> have
>     myArray["cheese"] = n++
> 
> Now you can use myArray["something"] in an expression and get back
> the number that was stored for that string (or a null string equivalent
> to arithmetic 0 if that index was never stored).
> 

echo "abcde c"| awk '{ for (x=0;x<length($1);x++) {
    a[substr($1,x,1)]=x;}; print a[$2]; }'

-- 
Luuk