RosettaCodeData/Task/URL-encoding/AWK/url-encoding.awk

BEGIN {
  for (i = 0; i <= 255; i++)
    ord[sprintf("%c", i)] = i
}

# Encode string with application/x-www-form-urlencoded escapes.
function escape(str,    c, len, res) {
  len = length(str)
  res = ""
  for (i = 1; i <= len; i++) {
    c = substr(str, i, 1);
    if (c ~ /[0-9A-Za-z]/)
    #if (c ~ /[-._*0-9A-Za-z]/)
      res = res c
    #else if (c == " ")
    # res = res "+"
    else
      res = res "%" sprintf("%02X", ord[c])
  }
  return res
}

# Escape every line of input.
{ print escape($0) }