BASH If Command Not Found - bash

Question

I have a slight problem with my BASH script that I do not know the cause.
Please take a look at this simple script.
#!/bin/bash
# Given two integers X and Y. find their sum, difference, product, and quotient
# Constraints
# -100 <= X,Y <= 100
# Y != 0
# Output format
# Four lines containing the sum (X+Y), difference (X-Y), product (X x Y), and the quotient (X // Y) respectively.
# (While computing the quotient print only the integer part)
# Read data
echo "Please input for x and y!"
read x
read y
declare -i MIN=-100
declare -i MAX=100
# Checks if the valued read is in the constraints
if [ $x -gt $MAX ] || [ $x -lt $MIN ];
then
echo "Error!"
exit 1;
elif [ $y -gt $MAX ] || [$y -lt $MIN ] || [$y -eq 0];
then
echo "Error"
exit 1;
else
for operator in {"+","-","*","/",}; do echo "$x $operator $y" | bc; done
fi
The output of the script above is as follow.
Please input for x and y!
1
2
worldOfNumbers.sh: line 26: [2: command not found
worldOfNumbers.sh: line 26: [2: command not found
3
-1
2
0
As you can see, there is this [2: command not found. I believe there is something wrong with my syntax however I feel like I have typed the right one.
p.s. I use Oh My ZSH to run the program. I've also tried running in VS Code however the same thing arise.
Thank you for the help.

Answer 1

If you put your code through shellcheck, you'll see that it is due to the lack of spaces between your variable and your bracket. Bash is a space oriented language, and [ and ] are commands just like echo or printf.
Change
elif [ $y -gt $MAX ] || [$y -lt $MIN ] || [$y -eq 0];
to
elif [ $y -gt $MAX ] || [ $y -lt $MIN ] || [ $y -eq 0 ];
^ ^ ^
Arrows added to show where spaces were added.
You can see that [ is a command if you run this at your bash prompt:
$ which [
[: shell built-in command
Because you do not have a space between [ and 2, bash assumes that you are trying to run a command called [2 and that command does not exist, as seen by your error message.

Answer 2

I seemed to fix it. Here is the code.
#!/bin/bash
# Given two integers X and Y. find their sum, difference, product, and quotient
# Constraints
# -100 <= X,Y <= 100
# Y != 0
# Output format
# Four lines containing the sum (X+Y), difference (X-Y), product (X x Y), and the quotient (X // Y) respectively.
# (While computing the quotient print only the integer part)
# Read data
echo "Please input for x and y!"
read x
read y
declare -i MIN=-100
declare -i MAX=100
# Checks if the valued read is in the constraints
if [ "$x" -gt $MAX ] || [ "$x" -lt $MIN ]
then
echo "Error!"
exit 1
elif [ "$y" -gt $MAX ] || [ "$y" -lt $MIN ] || [ "$y" -eq 0 ]
then
echo "Error"
exit 1
else
for operator in {"+","-","*","/",}; do echo "$x $operator $y" | bc; done
fi
There should be a space inside the [ expression ]. Pretty interesting!