unexpected result using regex in bash - regex

Question

I made a trying to make regex expression that will validate a number that is in the range of -100 to 100.
the regex expression I made is ^[-+]?([0-9][0-9]?|100)$.
I am looking for a pattern in a string not just an integer by itself.
this is my script:
#!/bin/bash
a="input2.txt"
while read -r line; do
mapfile -t d <<< "$line"
for i in "${d[#]}"; do
if [[ "$i" =~ ^[-+]?([0-9][0-9]?|100)$ ]]; then
echo "$i"
fi
done
done < "$a"
this is my input file:
add $s1 $s2 $s3
sub $t0
sub $t1 $t0
addi $t1 $t0 75
lw $s1 -23($s2)
the actual result is nothing.
the expected result:
75 -23($s2)

Answer 1

[...] denotes a set of characters, where the dash can be used to specify a character range. For instance, [4-6u-z] in a regexp means one of the characters 4,5,6,u,v,w,x,z. Your expression [1-200] simply matches the characters (digits) 0, 1 and 2.
In your case, I would therefore proceed in two steps: First, extract from your string the initial numeric parts, and then use arithmetic comparision on the result. For example (not tested!):
if [[ $i =~ ^-?[0-9]+ ]]
then
intval=${BASH_REMATCH[0]}
if (( intval >= -200 && intval <= 1000 ))
then
....
See the bash man page for an explanation of the BASH_REMATCH array.

Answer 2

#first store your file in an array so that we could pass thru the words
word_array=( $(<filename) )
for i in "${word_array[#]}"
do
if [[ $i =~ ^([[:blank:]]{0,1}-?[0-9]+)([^[:digit:]]?[^[:blank:]]*)$ ]]
#above line looks for the pattern while separating the number and an optional string
#that may follow like ($s2) using '()' so that we could access each part using BASH_REMATCH later.
then
#now we have only the number which could be checked to fall within a range
[ ${BASH_REMATCH[1]} -ge -100 ] && [ ${BASH_REMATCH[1]} -le 100 ] && echo "$i"
fi
done
Sample Output
75
-23($s2)
Note : The pattern might need a bit more testing, but you could imbibe the idea.