convert string to int

testac · 07-06-2010, 03:01 AM

Hi ,

Iam trying to check a value less than or equals 0.The value iam getting is after doing grep a file . but its throwing error .

Code:

VAL_5Y=`grep "VAL_5Y=" t.txt| cut -d\= -f2`
VAL_5Y=`expr ${VAL_5Y%\%}*1`
if [ "${VAL_5Y}" -eq 0 ]

When i execute this it throws

Code:

line 47: [: 516.23125*1: integer expression expected

please help

grail · 07-06-2010, 03:51 AM

Code:

if [ "${VAL_5Y}" -eq 0 ]

Quote:

line 47: [: 516.23125*1: integer expression expected

So what value is in VAL_5Y?? Assuming it is "516.23125*1", then this is clearly not an integer, hence the error message

testac · 07-06-2010, 04:02 AM

The value in VAL_5Y is 516.23125 which iam getting after grep from a file so its stored as a String so my task is to convert the VAL_5Y to integer so that i can use in if loop . How to do that . To convert to int i tried multiplying by 1 which is displayed in error .

ryan858 · 07-06-2010, 04:54 AM

Pretty sure that's a floating-point number, not an integer. Difference is the decimal point (.) ... You may also need to convert it from a string but maybe not.

Matter of fact, I don't even know if you can use floats in bash scripts... You are using a bash script correct?

Maybe try it in python or perl...

grail · 07-06-2010, 04:58 AM

Well as this number is not an integer you would have to either truncate or round as bash doesn't do floating point easily.
My solution was to truncate like so:

Code:

VAL_5Y=516.23125
VAL_TEST=$(echo $VAL_5Y | sed 's/\..*//')

if [[ $VAL_TEST -eq 0 ]]
then
    <do blah>
else
    <do blah2>
fi

Obviously for rounding you would need to construct your test. You also have the choice of using bc but I am not suitably skilled to explain how.

ryan858 · 07-06-2010, 05:05 AM

Using bc.

Code:

echo "scale=4; $VAL_5Y" | bc

You might have to adapt that, I just grabbed it off google. See http://www.novell.com/coolsolutions/tools/17043.html for more info.

Also, just cause I can:

Code:

\* C Code *\
#include <stdio.h>

int main() {
  float myFloat = 516.23125 * 1;
  printf("%d", myFloat);
  return 0;
}

And then you could use argv to grab the output of grep, etc,etc.
And really the only relevent part is

Code:

float myFloat = 516.23125 * 1;

testac · 07-06-2010, 10:22 AM

its a bash script and the number can be floating point as in this case.
my main concern is to check if number is greater than or equal to zero. surely i can try ryan and grail approach.Very high probability that the number will have left part of decimal point so surely can try out truncating post decimal and check for zero condition.

AnanthaP · 07-06-2010, 07:39 PM

if [ `expr $VAL_5Y / 1` -le 0 ]
..

everToulouse · 07-06-2010, 10:12 PM

Code:

VAL_5Y="516.23125"
IFS='.' read int dec <<< "$VAL_5Y"
if (( dec ))
then echo "VAL_5Y is greater than 0"
elif (( int >= 0 ))
then echo "VAL_5Y is greater than or equal to 0"
else echo "VAL_5Y is NOT greater than o equal to 0"
fi