tolower & toupper

Question

can anyone tell me how tolower and toupper expression works?

like what happend if its number or sumthin else ? like below.. v

*tolower('5')
*tolower('?')
*toupper('7')
*toupper('?')

Answer 1

If the evaluated character doesn't have a lowercase counterpart, nothing will be changed.

Answer 2

Stays the same?

Answer 3

ohh thanks... i think so too .. but.. i was uncertain of it so.. yea... lol.. thanks