Could someone please explain the concept of associative arrays in AWK programming?
 

Please explain the concept of associative arrays in awk programming with a few examples. I tried to find the good links about the same topic in internet and in our forum, but i did not find any good links to understand/get in-depth knowledge on the same topic. if you know any pointers to the same topic, please do provide.

It's really quite simple. Ordinarily, an array has a numeric index:
An associative array can use a string as a sort of index, making the array behave a bit like a key-value store:
Here's the chapter on arrays from the O'Reilly sed & awk book.

And here's the array section of the gawk user's guide.

http://www.gnu.org/software/gawk/man...de/Arrays.html

It should be noted that in awk, all arrays are associative. Even numbers like 1,2,3 are stored as simple text strings, not digits.

Thank you very much for your reply.
 

Could you please explain the behavior of the below awk code.?

awk '{ vec[$1]+=1 }
END { for (i in vec)
{print i vec[i] }'

My understanding: The vec[$1] points to the first field in the first line and it stores the same. The vec[$1]+=1
increases the value by 1 that means it proceeds to the next line and captures the first field in the second line. is it correct?.

I would have to say the easiest process for learning something like this code would be to run it on a small file of known data and see what happens.

Just understand that the "$1" will be replaced by the contents of the first field, the result of which will be used as the index string.

So think about it; what happens if the first field on two lines is the same, and what happens if they are different?

@OP: you may like to know that some langs eg Perl use the term 'hash' (as in hash table, not passwd hashing) for the same technique. :)