大小写转换

;将第一个字符串转化为大写，第二个字符串转化为小写

assume cs:code,ds:data

data segment

db 'BaSic',0

db 'iNfOrMatiOn',0

data ends

code segment

start:

mov ax,data

mov ds,ax

mov bx,0

call upcase

call lowcase

mov ax,4c00H

int 21H

；将第一个字符串转化为大写

upcase:

mov cl,[bx]

mov ch,0

jcxz s0

and cl,0dfH

mov [bx],cl

inc bx

jmp short uppcase

s0:

inc bx

ret

；将第二个字符转换为小写

lowcase:

mov cl,[bx]

mov ch,0

jcxz s1

or cl,20H

mov [bx],cl

inc bx

jmp short lowcase

s1:

ret

code ends

end start