while { this[i]!="" | that[j]!="" ){
    echo "this[i] loves that[j]";
    i++;j++;
}

here is some example in bash that might help
#!/bin/sh

FOO=( bar string 'some text')
foonum=${#FOO}

for ((i=0;i<$foonum;i++)); do
   echo ${FOO[${i}]}

done

produces -->>
bar
string
some text