pb heat 2

#!/bin/bash

if [ $# -ne 3 ]; then
    echo "Usage: $0 <num1> <op> <num2>!"
    exit 1
fi

case $2 in
    +) res=$(($1+$3));;
    -) res=$(($1-$3));;
    \*) res=$(($1*$3));;
    /) res=$(($1/$3));;
    *)
        echo "invalid op"
        exit 1;;
esac

echo = $res