String increment in UNIX

Shell Programming and Scripting
1

Hi,

I am able to increment numbers but unable to increment the charters in unix -AIX.

Source : AAA BB CCC
Increment Number : 5

OUTPUT:

AAA BB CCC
AAA BB CCD
AAA BB CCE
AAA BB CCF
AAA BB CCG

Thanks
onesuri

2

What are "the charters in unix"?

What comes after AAA BB CCZ? (AAA BB CC0, AAA BB CCa, AAA BBB CC[, AAA BB CD0, AAA BB CDa, or something else?) What characters are included in the character set for this exercise and in what order do they appear?

3

Try this bash solution (assuming AAA BB CDA comes after AAA BB CCZ and AA comes after Z):

#!/bin/bash
S="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
function inc
{
    local I F B
    F=${1%?}
    B=${1#$F}

    case "$B" in
       (\ ) echo "$(inc "$F") " ;;
       (Z) [ -z "$F" ] && echo AA || echo "$(inc "$F")A" ;;
       (*) echo "$F${S:1+36#$B:1}"
    esac
}

read -p "Source : " src
read -p "Increment Number : " cnt

for((i=0;i<cnt;i++)) {
    echo "$src"
    src=$(inc "$src")
}
4

Here's another solution in bash:

#!/bin/bash
#
#
#

# check command-line for filename and
# number to increment by
if [ $# -ne 2 ]
then
    echo "Usage: ${0##*/} \"<string>\" <increment #>"
    exit 1
fi

# store the values
str=$1
i=$(expr $2 + 1 )

# loop through file and increment last character
echo $str
for((x=1;x<$i;x++))
do
    lastChar=$(echo $str | awk '{print substr($0,length($0),1)}')
    incrLetter=$(echo $lastChar | tr 'A-Y' 'B-Z')
    newStr=$(echo $str | sed "s/.$/$incrLetter/")
    echo $newStr
    str=$newStr
done

# done
exit 0

./incAlpha.sh "AAA BB CCC" 5
AAA BB CCC
AAA BB CCD
AAA BB CCE
AAA BB CCF
AAA BB CCG
AAA BB CCH

289e80450dacb315df8e7ae3eaf1ed3d

5 
#!/bin/ksh93

function incstring
{
   src=$1

   typeset -i len=${#src}
   max=$(( len - 1))

   new=""
   typeset -i dec 
   carry=0

   while ((len--))
   do
      last=${src:$len:1}
      dec=$(printf "%u" "'$last")
      (( dec != 32 )) && {
         (( len == max )) && (( dec++ ))
         (( carry == 1 )) && { (( dec++ )); carry=0; } 
         carry=0
         (( dec > 90 )) && { dec=65; carry=1; } 
      } 
      ascii=$(printf \\$(($dec/64*100+$dec%64/8*10+$dec%8)))
      new=${ascii}${new}
   done

   echo $new
}


read str?"Source: "
read cnt?"Count: " 

for ((i=0; i < cnt; i++)) {
    str=$(incstring "$str")
    echo $str
}
1 Like
6

@fpmurphy - Nice solution, I like the shell conversion to dec I haven't come across that before.

A slight tweak is probably required to ensure that "ZZ" increments to "AAA":

   ((carry)) && new="A$new"
   echo $new