bash length

#!/bin/sh

i=0
max=100000
string=$(seq -s '' 1000)

if [ "$1" = len ]; then
    while [ $i -lt $max ]; do
        [ -z "$string" ]
        i=$((i+1))
    done
else
    while [ $i -lt $max ]; do
        [ "${#string}" -ne 0 ]
        i=$((i+1))
    done
fi