Count occurences of a special character in a file - bash

Question

I am writing a bash script that will count occurences of [], (), {}, '', "", `` and // so that i can debug other scripts for missing one of them.
Here is the code:
a=0; b=0; cc=0; d=0; e=0; f=0; g=0; h=0; i=0; j=0 # set default values
squote=`echo -e "\x27"`
dquote=`echo -e "\x22"`
while IFS= read -r -n1 c; do
[ "$c" == "[" ] && (( a++ ))
[ "$c" == "]" ] && (( b++ ))
[ "$c" == "(" ] && (( cc++ )) # i imported this line from another online script, is there a reason why the author avoids (( c++ )) ?
[ "$c" == ")" ] && (( d++ ))
[ "$c" == "{" ] && (( e++ ))
[ "$c" == "}" ] && (( f++ ))
[ "$c" == "\x27" ] && (( g++ )) # single quote
[ "$c" == "$dquote" ] && (( h++ )) # double quote
[ "$c" == '`' ] && (( i++ )) # back tick
[ "$c" == '/' ] && (( j++ )) # forward slash
done < "$1"
echo '[]'="$a,$b"
echo '()'="$cc,$d"
echo '{}'="$e,$f"
echo "$squote" ="$g"
echo "$dquote" ="$h"
echo '``'="$i"
echo '/'="$j" # when used this way: /hello/
Questions:
1) why the cc++ instead of c++
2) why some results don't come out right at all.
3) How to annotate the special characters the right way.
Thank you in advance for your help.

Answer 1

some simplifications and functional script
#!/bin/bash
a=0; b=0; c=0; d=0; e=0; f=0; g=0; h=0; i=0; j=0
while read -r -n1 char; do
case "$char" in
"[" ) (( a++ )) ;;
"]" ) (( b++ )) ;;
"(" ) (( c++ )) ;;
")" ) (( d++ )) ;;
"{" ) (( e++ )) ;;
"}" ) (( f++ )) ;;
"'" ) (( g++ )) ;;
'"' ) (( h++ )) ;;
'`' ) (( i++ )) ;;
'/' ) (( j++ )) ;;
esac
done <<< "[]{}()/"$'\x60'$'\x22'$'\x27' # $'\x60' == backtick
echo '[]'="$a,$b"
echo '()'="$c,$d"
echo '{}'="$e,$f"
echo "'" ="$g"
echo '"' ="$h"
echo '`'="$i"
echo '/'="$j"
output
[]=1,1
()=1,1
{}=1,1
' =1
" =1
`=1
/=1
nota:
prefer: dquote=$( echo -e "\x22" ) # and not ``
better: dquote=$'\x22' # or \042 octal
simpler: dquote='"'
to check script and learn, I suggest to install shellcheck or use https://www.shellcheck.net/
initially:
[ "$char" == "[" ] && (( a++ ))
[ "$char" == "]" ] && (( b++ ))
[ "$char" == "(" ] && (( c++ ))
[ "$char" == ")" ] && (( d++ ))
[ "$char" == "{" ] && (( e++ ))
[ "$char" == "}" ] && (( f++ ))
[ "$char" == "'" ] && (( g++ ))
[ "$char" == '"' ] && (( h++ ))
[ "$char" == '`' ] && (( i++ ))
[ "$char" == '/' ] && (( j++ ))
but unnecessary tests are systematically performed.
we can also use:
if [[ $char == "[" ]]; then (( a++ ))
elif [[ $char == "]" ]]; then (( b++ ))
...
but performances with 10,000 iterations:
if > if elif > case
6720 ms > 2895 ms > 2073 ms