version_comp

version_comp

function zeropadl () {
  result="$1"
  while [[ ${#result} -lt $#2 ]]
  do
    result="0$result"
  done
  echo -n "$result"
}

function zeropadr () {
  result="$1"
  while [[ ${#result} -lt $#2 ]]
  do
    result="${result}0"
  done
  echo -n "$result"
}

function version_comp () {
    if [[ $1 == $2 ]]
    then
        return 0
    fi
    # setting the field seperator to . allows us to chop the segments up
    # easily.
    local IFS=.
    local i ver1=($1) ver2=($2)
    # Handle the case where ver2 has more segments than ver1 by padding with
    # zeros
    for ((i=${#ver1[@]}; i<${#ver2[@]}; i++))
    do
        ver1[i]=0
    done

    # Pad the initial segment of each version with leading zeros.
    ver1[0]="$(zeropadl "${ver1[0]}" $((${#ver1[0]}+${#ver2[0]})))"
    ver2[0]="$(zeropadl "${ver2[0]}" $((${#ver1[0]}+${#ver2[0]})))"

    # Pad subsequent segments of each version with trailing zeros.
    for ((i=1; i<${#ver1[@]}; i++))
    do
      ver1[$i]="$(zeropadr "${ver1[$i]}" $((${#ver1[$i]}+${#ver2[$i]})))"
      ver2[$i]="$(zeropadr "${ver2[$i]}" $((${#ver1[$i]}+${#ver2[$i]})))"
    done

    for ((i=0; i<${#ver1[@]}; i++))
    do
        # Handle the case where ver1 is has more segments than ver2
        if [[ -z ${ver2[i]} ]]
        then
            ver2[i]=0
        fi

        # Compare lexicographically.
        if [[ ${ver1[i]} > ${ver2[i]} ]]
        then
            return 1
        fi
        if [[ ${ver1[i]} < ${ver2[i]} ]]
        then
            return 2
        fi
    done
    return 0
}