I have been using a pretty basic, and for the most part straight forward, method to converting base-10 numbers {1..256} to base-4 or quaternary numbers. I have been using simple division $(($NUM/4)) to get the main result in order to get the remainders $(($NUM%4)) and then printing the remainders in reverse to arrive at the result. I use the following bash script to do this:
#!/bin/bash
NUM="$1"
main() {
local EXP1=$(($NUM/4))
local REM1=$(($NUM%4))
local EXP2=$(($EXP1/4))
local REM2=$(($EXP1%4))
local EXP3=$(($EXP2/4))
local REM3=$(($EXP2%4))
local EXP4=$(($EXP3/4))
local REM4=$(($EXP3%4))
echo "
$EXP1 remainder $REM1
$EXP2 remainder $REM2
$EXP3 remainder $REM3
$EXP4 remainder $REM4
Answer: $REM4$REM3$REM2$REM1
"
}
main
This script works fine for numbers 0-255 or 1-256. But beyond this(these) ranges, results become mixed and often repeated or inaccurate. This isn't so much of a problem as I don't intend to convert numbers beyond 256 or less than 0 (negative numbers [yet]).
My question is: "Is there a more simplified method to do this, possibly using expr or bc?
Create a look-up table taking advantage of brace expansion
$ echo {a..c}
a b c
$ echo {a..c}{r..s}
ar as br bs cr cs
$ echo {0..3}{0..3}
00 01 02 03 10 11 12 13 20 21 22 23 30 31 32 33
and so, for 0-255 in decimal to base-4
$ base4=({0..3}{0..3}{0..3}{0..3})
$ echo "${base4[34]}"
0202
$ echo "${base4[255]}"
3333