CODEWITHSUNDEEP
bashsplitsubstring
Roger
Roger

Reputation: 8576

Bash split substring

I am receiving numeric variables sometimes with 2, other times with 3 digits, like '321' and '32'. And I want to put a dot among each of the numbers. So if I receive '32', I got to echo '3.2' and if I receive '321' I echo '3.2.1'.

This is what I did:

S='321'
SL="${#S}" #string lentgh

n1=`echo $S | cut -c 1-1`
n2=`echo $S | cut -c 2-2`

if [ "$SL" -eq 2 ]; then
    echo $n1.$n2
elif  [ "$SL" -eq 3 ]; then
    n3=`echo $S | cut -c 3-3`
    echo $n1.$n2.$n3
else
    die 'Works only with 2 or 3 digits'
fi

My question is: is there any shorter way of doing the same thing?

UPDATE: Shorter but still verbose:

SL="${#1}" #string lentgh
S=$1
if [ "$1" -eq 3 ]; then
    $n3=".${S:2:1}"
fi
if  [ "$SL" -lt 2 ] && [ "$SL" -gt 3 ]; then
    die 'Works only with 2 or 3 digits'
fi

echo "${S:0:1}.${S:1:1}$n3"

UPDATE 1:

If I include the if block, the sed+regex version will be quite as long as the pure bash version:

SL="${#1}" #string lentgh
S=$1
N=$(echo $S | sed -r "s/([0-9])/\1./g")
echo ${N%%.}
if  [ "$SL" -lt 2 ] && [ "$SL" -gt 3 ]; then
    die 'Works only with 2 or 3 digits'
fi

Or, using a one line sed+regex with two expressions:

SL="${#1}" #string lentgh
echo $1 | sed -e 's/\([[:digit:]]\)/.\1/g' -e 's/^\.//'
if  [ "$SL" -lt 2 ] && [ "$SL" -gt 3 ]; then
    die 'Works only with 2 or 3 digits'
fi

Thanks.

Upvotes: 2

Views: 1753

Answers (4)

f4m8
f4m8

Reputation: 410

I prefer also the sed for that:

echo 321 | sed -e 's/\([[:digit:]]\)/.\1/g' | cut -b2- -> 3.2.1

echo 32 | sed -e 's/\([[:digit:]]\)/.\1/g' | cut -b2- -> 3.2

Or without cut it looks like this

echo 321 | sed -e 's/\([[:digit:]]\)/.\1/g' -e 's/^\.//'

Upvotes: 2

carlpett
carlpett

Reputation: 12583

It's not that pretty, but at least it's short:

num=$(echo $S | sed -r "s/([0-9])/\1./g")
echo ${num%%.}

Upvotes: 2

phoxis
phoxis

Reputation: 61910

Here is one. This will work for any string length.

#!/bin/bash

#s is the string
#fs is the final string

echo "Enter string"
read s

n="${#s}"
fs=""

i=0
for ((i=0; i<n; i++))
  do
   fs="$fs.${s:i:1}"
done

#find the length of the final string and
#remove the leading '.' 

n="${#fs}"
fs="${fs:1}"

echo "$fs"

Upvotes: 2

Blagovest Buyukliev
Blagovest Buyukliev

Reputation: 43508

S='321'
perl -e "print join '.', split //, shift" "$S"

Upvotes: 1

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