Comparing two numbers with decimal point - Page 2

ahmad.diab · #1 (**permalink**) 4 Weeks Ago

Quote:

Originally Posted by Scrutinizer

Bash I am not surprised since I gather that is not a happy marriage with Solaris (is it even installed on your system?). However the problem with posix compliant version puzzles me. What is the output of this command on your system:

Code:

echo "12.13>12.14"|bc; echo "12.14>12.13"|bc

Code:

Yes I have bash version 3.0 on my system and the error massage when putting 

bash code
syntax error on line 1, teletype
bash: ((: > 0 : syntax error: operand expected (error token is "> 0 ")

posix code
syntax error on line 1, teletype
bash: [: -gt: unary operator expected

Scrutinizer · #2 (**permalink**) 4 Weeks Ago

OK, and:

Code:

echo "12.13 > 12.14"|bc; echo "12.14 > 12.13"|bc

ahmad.diab · #3 (**permalink**) 4 Weeks Ago

Quote:

Originally Posted by Scrutinizer

OK, and:

Code:

echo "12.13 > 12.14"|bc; echo "12.14 > 12.13"|bc

just it give me the same error in below and that's it

Code:

syntax error on line 1, teletype
syntax error on line 1, teletype

radoulov · #4 (**permalink**) 4 Weeks Ago

Quote:

Originally Posted by ahmad.diab

[...]
SunOS server2 5.10

On Solaris you can also use ksh93 (you may have it under /usr/dt/bin/dtksh), zsh or expr.

Code:

% zsh -c '((1.20 > 1.3)) && print ok || print ko'
ko

cfajohnson · #5 (**permalink**) 4 Weeks Ago

Quote:

Originally Posted by radoulov

Code:

$ bash -c '(( $(expr 1.20 \> 1.3) == 1 )) && echo ok || echo ko' 
ko

Code:

bash -c 'case $(expr 1.20 \> 1.3) in (1) echo ok;; (*) echo ko;; esac'
ko

Like bash, expr only does integer arithmetic; you cannot use it with decimal fractions.

In any POSIX shell, you can strip the fraction and compare the integer portions. If they are equal, then compare the decimals:

Code:
if [ ${1%.*} -gt  ${2%.*} ]
then
  printf "%s is larger than %s\n" "$1" "$2"
elif [ ${1%.*} -eq  ${2%.*} ]
then
  : decimal comparison left as exercise for the reader 
else
  printf "%s is smaller than %s\n" "$1" "$2"
fi

radoulov · #6 (**permalink**) 3 Weeks Ago

Quote:

Originally Posted by cfajohnson

Like bash, expr only does integer arithmetic; you cannot use it with decimal fractions.

I had that doubt after posting the example. Thank you for pointing it out.

Quote:

In any POSIX shell, you can strip the fraction and compare the integer portions. If they are equal, then compare the decimals:

Code:

 if [ ${1%.*} -gt  ${2%.*} ]
then
  printf "%s is larger than %s\n" "$1" "$2"
elif [ ${1%.*} -eq  ${2%.*} ]
then
  : decimal comparison left as exercise for the reader 
else
  printf "%s is smaller than %s\n" "$1" "$2"
fi

I like this approach.
Thanks again!

Scrutinizer · #7 (**permalink**) 4 Weeks Ago

OK, and what about:

Code:

echo "12.13>12.14"|/usr/bin/xpg6/bc; echo "12.14>12.13"|/usr/bin/xpg6/bc

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