how will I fix the echo when counting chars in a string - bash

Question

I have an issue with the echo in the for loop, as I want to count string chars especailly for "*" it but it prints all the files in current directory.
clearvar() {
int=0
str=0
uniqchar=0
}
countstring(){
for c in $(echo "${1}" | fold -w1); do
echo "$c"
if [[ $c == [0-9] ]];then
int=$(( $int + 1 ))
elif [[ $c == [a-Z] ]];then
str=$(( $str + 1 ))
else
uniqchar=$(( $uniqchar + 1 ))
fi
done
}
while [ $# -gt 0 ];do
echo "Argument input: $1"
read -p "Input: " string
rmws=$(echo $string | tr -d " ")
mashed=$rmws$1
countstring $mashed
echo -e "int: $int\nstr: $str\nuniquechar: $uniqchar\nWhole string: $mashed"
clearvar
shift
done
Example output:
Argument input: io1
Input: fj^*23
f
j
^
file1
file2
file3
2
3
i
o
1
int: 3
str: 4
uniquechar: 4
Whole string: fj^*2wio1
it interprets as echo * instead of echo "*".
so I expect it to not print out the file names.

Answer 1

rmws=$(echo $string | tr -d " ")
If string=* this just executes echo * and expands the *.
The same happens in:
countstring $mashed
Both these expansions are unquoted. Quote them in double quotes. As a rule of a thumb - always use double quotes.
Also the same happens in the for loop:
for c in $(echo "${1}" | fold -w1)
the expansion, as elsewhere, is unquoted, so * expands. You have to quote. That's why the for i in $(..) is considered bad style - because such bugs happen. You can't do for i in "$(...)" because then you would iterate over one element. To iterate over lines or elements in a stream use a while IFS= read -r loop. You can print every character on each separate line with ex. sed 's/./&\n/g' and iterate over lines, or use bash extension read -n1 to read one character.
while IFS= read -r -n1 c; do
..
done <<<"$1"
The <<<"$1" is a bash's "here string".
You don't need $ in arithmetic expansion. Just:
int=$(( int + 1 ))
str=$(( str + 1 ))
uniqchar=$(( uniqchar + 1 ))
or in bash you can even do:
(( int++ ))
# and so on
Your script could become:
clearvar() {
int=0
str=0
uniqchar=0
}
countstring(){
while IFS= read -r -n1 c; do
echo "$c"
if [[ $c == [0-9] ]];then
(( int++ ))
elif [[ $c == [a-Z] ]];then
(( str++ ))
else
(( uniqchar++ ))
fi
done <<<"$1"
}
while [ $# -gt 0 ]; do
echo "Argument input: $1"
read -p "Input: " string
rmws="$(echo "$string" | tr -d " ")"
mashed="$rmws$1"
countstring "$mashed"
echo "int: $int"
echo "str: $str"
echo "uniquechar: $uniqchar"
echo "Whole string: $mashed"
clearvar
shift
done
Notes:
echo has portability issues. Prefer to use printf instead.
I prefer while (($#)); do in place of while [ $# -eq 0 ]; do.
PS. I would use tr:
countstring() {
printf "%s" "$1" | tr -cd '[0-9]' | wc -c
printf "%s" "$1" | tr -cd '[a-zA-Z]' | wc -c
printf "%s" "$1" | tr -d '[0-9a-zA-Z]' | wc -c
}