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How to check whether a string is number or not

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regex, regular expressions

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Old 09-21-2005
shihabvk shihabvk is offline
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How to check whether a string is number or not

Hi ,
I am facing a problem .. which looks simple... but took 2 days of mine.. even now it is not solved completely..

I have one variable..., want to know whether that variable contains number... canbe +ve or -ve ...

Values
+35 --- number
-43 --- number
45A -- non number
34+45 -- non number

please help me
Shihab
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Old 09-21-2005
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vino vino is offline Forum Advisor  
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Look at the solution given in this post

Let me knows if it falters for any condition.

Vino

Last edited by vino; 09-21-2005 at 05:42 AM..
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Old 09-21-2005
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RishiPahuja RishiPahuja is offline
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MySQL

Another solution vaild only for integers, decimals not allowed

#!/bin/ksh
echo "Enter val : \c"
read num
expr $num + 1 2> /dev/null
if [ $? = 0 ]
then
echo "Val was numeric"
else
echo "Val was non-numeric"
fi

rishi

Last edited by RishiPahuja; 09-21-2005 at 05:58 AM..
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Old 09-21-2005
shihabvk shihabvk is offline
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Hi rishi ,
It won't work if the number is like +567
example expr +567 + 1 .. will fail


Regards
Shihab
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Old 09-21-2005
sanjustudy sanjustudy is offline
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number or not

if u r using tcl or perl there is finction calles isnumber

if [ isnumber $a ] {
}
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Old 09-21-2005
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RishiPahuja RishiPahuja is offline
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MySQL

Quote:
Originally Posted by shihabvk
Hi rishi ,
It won't work if the number is like +567
example expr +567 + 1 .. will fail


Regards
Shihab

A small edit Shihab,

#!/bin/ksh
echo "Enter val : \c"
read num
expr "$num + 1" 2> /dev/null
if [ $? = 0 ]
then
echo "Val was numeric"
else
echo "Val was non-numeric"
fi

Note the double qutoes around the expression.

Rishi
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Old 09-21-2005
matrixmadhan matrixmadhan is offline Forum Advisor  
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how abt this,


Code:
[[ `echo $num | sed 's/^[-+0-9][0-9]*//' | wc -c` -eq 1 ]] && echo "itz number" && exit 0
echo "itz not number"

not thoroughly tested
plz let me know, if it faints somewhere
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