U_Case Function in Assembly

include irvine32.inc

.data
source byte "my name is usman and i am not A KHAN",0
msg   byte "After Iviking U-Case function: ",0
msg1 byte "String Source is = ",0

.code
Main proc
call clrscr
call crlf
mov edx,offset msg1
call writestring
call crlf

call crlf
mov edx,offset source
call writestring
call crlf


call crlf
mov edx,offset msg
call writestring
call crlf


invoke str_ucase , addr source


call crlf
mov edx,offset source
call writestring
call crlf

exit
main endp
end main