I'm relatively new to bash programming and i am currently creating a simple calculator.
It needs to use floating point numbers and check they are so.
I have a checkNumbers function:
function checkNumber {
regExp=[0-9]
if [ $testNo =~ $regExp ]
then
echo "That is a number!"
let check=1
else
echo "Damn! Not A Number!"
fi
}
where i get the user to input a number like this:
while [ $check -eq 0]
do
echo "Please enter a number
read testNo
echo ""
checkNumber
done
This does not work, i get this error:
./calculator.sh: line 39: [: =~: binary operator expected
line 39 is:
if [ $testNo =~ $regExp ]
I have tried lots of Regular Expressions like:
^*[0-9]*$
and
^*[0-9]\.[0.9]*$
etc etc.
also, i have tied other ways of performing the check:
case $testNo
in
^*[0-9]*$) echo "That is a number!";;
*) echo "Error! Not a number!";;
esac
and
if [ $testNo = ^*[0-9]*$ ]
then
echo "etc etc"
else
echo "oops"
fi
I also need this to work with floating point numbers.
could someone please let me know how i go about this?
This regex ^[-+]?[0-9]+\.?[0-9]*$
will match only digits with an optional .
:
$ echo 30 | grep -Eq '^[-+]?[0-9]+\.?[0-9]*$' && echo Match
Match
$ echo 30.10 | grep -Eq '^[-+]?[0-9]+\.?[0-9]*$' && echo Match
Match
$ echo 30. | grep -Eq '^[-+]?[0-9]+\.?[0-9]*$' && echo Match
Match
$ echo +30 | grep -Eq '^[-+]?[0-9]+\.?[0-9]*$' && echo Match
Match
$ echo -30 | grep -Eq '^[-+]?[0-9]+\.?[0-9]*$' && echo Match
Match
I think when you tried ^*[0-9]
you wanted ^[0-9]*
Rexeplanation:
^ # Match start of string
[-+]? # Match a leading + or - (optional)
[0-9]+ # Match one or more digit
\.? # Match a literal . (optional, escaped)
[0-9]* # Match zero or more digits
$ # Match the end of the string
Note: this matches numbers followed by a .
like 30.
, not sure if this is acceptable for you.
Edit: Don't quote the regex
testNo=30.00
if [[ $testNo =~ ^[+-]?[0-9]+\.?[0-9]*$ ]]; then
echo Match
fi
>>> Match