hacker range bash - case about tr switch signs

marek@ubuntu:~/dev/bash$ echo "int i=(int)5.8 (23 + 5)*2" | tr '()' '[]'
int i=[int]5.8 [23 + 5]*2
marek@ubuntu:~/dev/bash$ echo "int i=(int)5.8 (23 + 5)*2" | tr "(" "[" | tr ")" "]"