Hi guys...
Macbook Pro, 13", circa August 2012, OSX 10.7.5, default bash terminal.
I require the capability to convert +32767 to -32768 into signed hex words...
The example piece code below works perfectly except...
#/bin/bash
# sign.sh
# Unsign to sign...
while true
do
# I have used $(( ~n )), where n is a positive integer too.
# Test piece only hence no error checking at all.
read -p "Enter negative number -1 to -32768:- " num
if [ $num -le -1 ]
then
printf "$[ ( $num + 65536 ) ]\n"
else
printf "Zero or positive value entered, $num.\n"
fi
# Why a 64 bit _hex_ value here?
hex=$(printf "%04X\n" $num)
printf "$hex\n"
# I have to use this to correct.
if [ ${#hex} -gt 4 ]
then
hex="${hex:$[ ( ${#hex} - 4 ) ]:4}"
fi
printf "$hex\n"
done
Results:-
Last login: Sun Jun 8 19:52:33 on ttys000
AMIGA:barrywalker~> ./sign.sh
Enter negative number -1 to -32768:- 0
Zero or positive value entered, 0.
0000
0000
Enter negative number -1 to -32768:- 1
Zero or positive value entered, 1.
0001
0001
Enter negative number -1 to -32768:- -1
65535
FFFFFFFFFFFFFFFF
FFFF
Enter negative number -1 to -32768:- 32767
Zero or positive value entered, 32767.
7FFF
7FFF
Enter negative number -1 to -32768:- -32768
32768
FFFFFFFFFFFF8000
8000
Enter negative number -1 to -32768:- ^CAMIGA:barrywalker~>
AMIGA:barrywalker~> _
My question is this:-
Why does the line hex=$(printf "%04X\n" $num) not truncate the hex
string to 4 characters?
I have tried, %04X, %02X and %X along with $num and "$num" but I still have to use the extra code to correct to 4 hex characters.
TIA...