汇编语言

data segment ;定义数据段
infon db 0dh,0ah,'Please input a year: $'
i db 0dh,0ah,'quit"q" $'

Y db 0dh,0ah,'This is a leap year! $'
N db 0dh,0ah,'This is not a leap year! $'
e db 0dh,0ah,'no year! $'
w dw 0
buf db 8
db ?
db 8 dup(?)
data ends

stack segment stack
db 200 dup(0)
stack ends

code segment
assume ds:data,ss:stack,cs:code
start:mov ax,data
mov ds,ax

lea dx,infon ;在屏幕上显示提示信息
mov ah,9
int 21h

lea dx,buf ;从键盘输入年份字符串
mov ah,10
int 21h

mov cl, [buf+1]
lea di ,buf+2

push ax
zm:
mov al,[di]

cmp al,0dh
jz a5

cmp al,'9'
jg a0
cmp al,'0'
jl a0
inc di
jmp zm

a5:
pop ax
call datacate
call ifyears
jnc a2 ;有进位
jc a1 ;无进位

a1: lea dx,y
mov ah,9
int 21h
lea dx,i ;在屏幕上显示提示信息
mov ah,9
int 21h
call exit

a2: lea dx,n
mov ah,9
int 21h
lea dx,i ;在屏幕上显示提示信息
mov ah,9
int 21h
call exit

a0: lea dx,e
mov ah,9
int 21h
lea dx,i ;在屏幕上显示提示信息
mov ah,9
int 21h
call exit




exit: mov ah,0
int 16h
cmp ah,71h
mov ah,4ch
int 21h
ret

datacate proc near;
push cx;
dec cx
lea si,buf+2
tt1: inc si
loop tt1
pop cx
mov dh,30h
mov bl,10
mov ax,1
l1: push ax
sub byte ptr [si],dh
mul byte ptr [si]
add w,ax
pop ax
mul bl
dec si
loop l1
ret
datacate endp


ifyears proc near
push bx
push cx
push dx
mov ax,w
mov cx,ax
mov dx,0
mov bx,4
div bx
cmp dx,0
jnz lab1
mov ax,cx
mov bx,100
div bx
cmp dx,0
jnz lab2 ;不是0
mov ax,cx
mov bx,400
div bx
cmp dx,0
jz lab2 ;是0
lab1: clc ;清除标志位CF=0
jmp lab3
lab2: stc ;CF=1
lab3: pop dx
pop cx
pop bx
ret
ifyears endp
code ends
end start