UNIX for Dummies Questions & Answers

Hi

Can someone please explain the logic of awk arrays. I have been doing some reading but I dont understand this:

Code:

#!/usr/bin/gawk -f

{
        arr[$2]++;
}
end
{
for(i in arr)
{
        print arr[i],i
}
}

As I understand arr[] refs the arrays index, so while $2 is a string that cant be converted to a number its converted to 0 and incremented. What happens if $2 is a number and overwrites the value at an earlier index. Additionally in the for statement shouldnt arr[i] print the value of index i rather than the no of times of the value of index i.

Thanks for any explanations.

The index of the awk array need not be integer, it can be string as well.
For eg, arr[test] = 1

Awk array values will be initialised to zero always.
So by the statement, arr[$2]++, would mean that the first occurence of $2 will increment its value as 1 from 0.

The for loop in the above awk statement would ideally print the no of occurences of $2 (ie the second field)

Thanks tene

Makes a bit more sense now. Was confused as to what the ++ was incrementing.