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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
+
+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
+}
+
+isnum2() # string
+{
+ case $1 in
+ ?([-+])+([[:digit:]])?(.)*([[:digit:]])?([Ee]?([-+])+([[:digit:]])) )
+ return 0;;
+ ?([-+])*([[:digit:]])?(.)+([[:digit:]])?([Ee]?([-+])+([[:digit:]])) )
+ return 0;;
+ *) return 1;;
+ esac
+}
+
+isint() # string
+{
+ case $1 in
+ ?([-+])+([0-9]) )
+ return 0;;
+ *) return 1;;
+ esac
+}
+
+isint2() # string
+{
+ case $1 in
+ ?([-+])+([[:digit:]]) )
+ return 0;;
+ *) return 1;;
+ esac
+}