CODEWITHSUNDEEP
bashshell
shantanuo
shantanuo

Reputation: 32336

Convert to number

How do I convert a string to a number? The following Bash script does not work as expected.

#!/bin/sh

mynum="0.02"

if [[ $mynum -lt 1 ]];then
    echo "low"
else
    echo "high"
fi

Error message

stack.sh: line 5: [[: 0.02: syntax error: invalid arithmetic operator (error token is ".02")

Upvotes: 2

Views: 1107

Answers (3)

xiaofengmanlou
xiaofengmanlou

Reputation: 51

You can use "<"">" instead of -lt or -gt. For example:

a=0.09;[[ $a < 1 ]] && echo low ||echo big     
low
a=1.01;[[ $a < 1 ]] && echo low ||echo big    
big

Upvotes: -2

Mayank
Mayank

Reputation: 5728

The following worked for me. It's just the idea how you can use bc. Change the code as you wish.

mynum="1.02"

d=\`echo "$mynum-1" | bc\`
if [ "${d:0:1}" = "-" ]
then
    echo "low"
else
    echo "high"
fi

Upvotes: 2

geekosaur
geekosaur

Reputation: 61389

The problem is that bash normally only supports integer arithmetic; you will need to punt floating or complex math to dc or bc.

You may be able to cheat in this case:

case $mynum in
0 | 0.* | .* | -*)
    echo low
    ;;
*)
    echo high
    ;;
esac

But this obviously isn't generally applicable.

Upvotes: 3

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