Awk-- splitting a string into sub-strings with length n

Question

I am familiar with function split() which is used in awk programs. I was wondering how I can use it to split a string into smaller strings with length of n? Something like (n is set at 2):

input:

abcdefgh

output:

ab cd ef gh

Answer 1

Since you accepted a non-split() solution, here's one that's non-gawk-specific, briefer, and probably faster :-):

$ awk '{gsub(/.{2}/,"& ")}1' file
ab cd ef gh

$ awk '{gsub(/.{3}/,"& ")}1' file
abc def gh

Just like the loop-based one you accepted, it adds a trailing blank char when the input string is an exact multiple of the number of chars you want it split on.

Answer 2

Split function in (g)awk is meant to split a string on delimiters. It populates an array with fields that are delimited by the delimiter. Since your string has none and you basically want to split the string in chunks, you can use GNU awk feature of split which also creates an optional array based on separator.

gawk 'BEGIN {
    n = split ("abcdefgh", ary, /../, seps);
    for (i=1; i<=n; i++) 
       printf "%s%s", seps[i], (i<n?FS:RS)
}'
ab cd ef gh