$format = 'There are %1$d monkeys in the %s and %s ';
printf($format, 100, 'Chennai', 'Bangalore');
Expecting to output
"There are 100 monkeys in the Chennai and bangalore"
But, this will output
"There are 100 monkeys in the 100 and Chennai"
Because, the second and Third specifiers takes 1rst and 2nd arguments. Because it is not assigned with any arguments.