5 replies to this topic

[alice06]

Hi all

I hav written a very small shell script in bin bash & its not working. The script is ::

#!/bin/bash

i=1.0

while [ $i -le 3.0 ]

do

	i=`expr "$i + 0.5" | bc`;

	 echo "i=$i"

done

The error is :

line 6: [: 1.0: integer expression expected

I think the use of decimals in the while loop is creating problems.

Please help, in urgent need.

Regards
Alice

[DarkLordofthePenguins]

The bash shell doesn't have decimal or floating point types, only strings, integers, and arrays. If you want to use a decimal, either use ksh or emulate floating point arithmetic by using larger numbers and then inserting the decimal point in the output with sed or something. For instance:

#!/bin/bash

declare -i i=10

# use the number multiplied by 10

while [ $i -le 30 ]

do

	i=`expr "$i + 5" | bc`;

	 echo "i=$i" | sed "s/[0-9]$/\.&/" # sed inserts a decimal point before the last digit

done

I used "declare -i" here because otherwise, i is interpreted as a string, not an integer.

[alice06]

Hey DarkLordofthePenguins, Thanx a ton for replying.

Wid ur script, I was able to get my job done perfectly.

Thanx for helping me out, thank u very much.

Regards
Alice

[Smilex]

I read once that you should never use decimals for conditions and loops, I'm not so sure about this, so if there's anyone who knows better who could clarify that? :P
P.S: I didn't want to make a new thread just for that, since it's kind of on-topic here. I hope that's no problem? :P

[Alexander]

Smilex said:

I read once that you should never use decimals for conditions and loops

Fixed precision decimal numbers are likely to be incorrectly represented, 0.7 + 0.7 can often lead to 1.5 and other havok depending on the system and how the program uses them.

[Smilex]

thanks for the clarification