awk opposite of split - awk

Question

what would be an opposite of split() in awk?
Imagine I have array containig characters/integers.
What I've tried:
color = "#FFFF00";
printf("color original: %s\n", color);
split(color, chars, "");
joined = "";
for (i=1; i <= length(chars); i++) {
joined = joined + chars[i];
}
printf("color joined: %s\n", joined);
however the output is:
color original: #FFFF00
color joined: 0
that is of course incorrect.
UPDATE:
cool, ended up with the following code (inspired by join function present in answers):
color = "#FFFF00";
printf("color original: %s\n", color);
split(color, chars, "");
joined = "";
for (i=1; i <= length(chars); i++) {
joined = joined "" chars[i];
}
printf("color joined: %s\n", joined);
the trick was not to use + sign when joining things back

Answer 1

Here's a solution that doesn't rely on gawk or knowing the length of the array and lets you put a separator (space in this case) string between each array element if you like:
color = "#FFFF00"
printf "color original: %s\n", color
split(color, chars, "")
joined = sep = ""
for (i=1; i in chars; i++) {
joined = joined sep chars[i]
sep = " " # populate sep here with whatever string you want between elements
}
printf "color joined: %s\n", joined
I also cleaned up the incorrect use of printf and the spurious semi-colons.
In the above script split(color, chars, "") relies on having a version of awk that will split a string into an array given a null field separator, which is undefined behavior per POSIX, but that's not what this answer is about - the question is how to join array elements not how to split them.

Answer 2

Here is a way with POSIX Awk:
br = "red,orange,yellow,green,blue"
ch = split(br, de, ",")
print "original: " br
printf "joined: "
for (ec in de) printf ec == ch ? de[ec] "\n" : de[ec] "-"
Output:
original: red,orange,yellow,green,blue
joined: red-orange-yellow-green-blue

Answer 3

What you want (in your loop) is string concatenation.

Answer 4

Similar to previous answers and less elegant, but easy and short:
color = "#FFFF00"
printf "color original: %s\n", color
split(color, chars, "")
for (i=1; i<=length(chars); i++) {
(i==1) ? joined = chars[i] : joined = joined" "chars[i] # Define separator here
}
printf "color joined: %s\n", joined

Answer 5

Knowing that the opposite of split() is join(), a mere Google Search gives me this page, which seems to contain the solution : http://www.gnu.org/software/gawk/manual/html_node/Join-Function.html . It joins all the elements of an array together, and returns the corresponding string.
['f','o','o'] => "foo"
Have fun