Why is Oracle's to_char() function adding spaces?

Question

Why is Oracle\'s to_char() function adding spaces?

select length(\'012\'), 
       length(to_char(\'012\')), 
       length(to_char(\'12\', \'000\')         


        

Answer 1

To make the answers given more clear:

select '['||to_char(12, '000')||']', 
       '['||to_char(-12, '000')||']', 
       '['||to_char(12,'FM000')||']' 
from dual


[ 012]                      [-012]                       [012]