filelength=wc -l array.txt
for ((i=1;i<=filelength;i+=1)) do 
if [ sed -n $i/<key>.*<\/key>/p array.txt ]
for ((j=i;j<=filelength;j+=1)); do
if [ sed -n $i /<string>.*<\/string>/p array.txt ] then
# insert code that will take key and string and insert them into an array
fi
done
fi
done