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#From: jrmartin@rainey.blueneptune.com (James R. Martin)
#Newsgroups: comp.unix.shell
#Subject: Re: testing user input on numeric or character value
#Date: 26 Nov 1997 01:28:43 GMT
# isnum returns True if its argument is a valid number,
# and False (retval=1) if it is any other string.
# The first pattern requires a digit before the decimal
# point, and the second after the decimal point.
# BASH NOTE: make sure you have executed `shopt -s extglob' before
# trying to use this function, or it will not work
function isnum # string
{
case $1 in
?([-+])+([0-9])?(.)*([0-9])?([Ee]?([-+])+([0-9])) )
return 0;;
?([-+])*([0-9])?(.)+([0-9])?([Ee]?([-+])+([0-9])) )
return 0;;
*) return 1;;
esac
}
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