Using awk printf to urldecode text

Question

I'm using awk to urldecode some text.

If I code the string into the printf statement like printf "%s", "\x3D" it correctly outputs =. The same if I have the whole escaped string as a variable.

However, if I only have the 3D, how can I append the \x so printf will print the = and not \x3D?

I'm using busybox awk 1.4.2 and the ash shell.

Answer 1

This relies on gnu awk's extension of the split function, but this works:

gawk '{ numElems = split($0, arr, /%../, seps);
        outStr = ""
        for (i = 1; i <= numElems - 1; i++) {
            outStr = outStr arr[i]
            outStr = outStr sprintf("%c", strtonum("0x" substr(seps[i],2)))
        }
        outStr = outStr arr[i]
        print outStr
      }'