所以我在汇编语言x86中遇到问题，我必须提示用户输入一个数字并打印星期几。所以（0 =星期日，1 =星期一..etc）我找到了行索引和列大小，但我遇到了问题。这是我到目前为止的代码。
.model small
.data
message db "Please enter a number between 0 and 6$"
week dword "Sunday___$", "Monday___$", "Tuesday__$", "Wednesday$"
dword "Thursday_$", "Friday___$", "Saturday_$"
Rowsize = ($ - week)
.code
row_index = 1
column_index = 2
main proc
mov ax,@data
mov ds, ax
mov ah,9
mov dx,OFFSET message
int 21h
mov ah,1
int 21h
mov bx, offset week
add bx, Rowsize * row_index
mov si, column_index
mov ax, week[bx + si * TYPE week]
sub al, 30h
mov dl, al
mov ah, 2
int 21
mov ax, 4c00h
int 21h
int 20h
main endp
end
例如
; The following example locates the value at row 1, column2
.model small
.data
tableB Byte 10h, 20h, 30h, 40h, 50h
Rowsize = ($ - tableB)
Byte 60h, 70h, 80, 90, 0A0h
Byte 0B0h, 0C0h, 0D0h, 0E0h, 0F0h
.code
main proc
row_ index = 1
column_index = 2
mov ebx, offset tableW ;table offset
add ebx, Rowsize * row_index ; row offset
mov esi, column_index
mov al, [ebx + esi] ; AL = 80h
main endp
end
Months.asm
.model small
.stack 100h ;◄■■ STACK!!!
.data
message db "Please enter a number between 0 and 12 : ",0dh,0ah,'$'
week db "January $",0dh,0ah,'$'
db "february $",0dh,0ah,'$'
db " March $",0dh,0ah ,'$'
db " April ",0dh,0ah,'$'
db " May $ ",0dh,0ah,'$'
db " June $",0dh,0ah,'$'
db " July $",0dh,0ah,'$'
db " August $",0dh,0ah,'$'
db "September$",0dh,0ah ,'$'
db " October $",0dh,0ah,'$'
db "November $",0dh,0ah ,'$'
db "December$ ",0dh,0ah,'$'
enters db 13
bye db 0dh, 0ah, "BYE",0dh, 0ah, '$'
.code ;◄■■ CODE!!!
main proc
mov ax,@data
mov ds, ax
L1:
mov ah,9
mov dx,OFFSET message
int 21h
mov ah,1
int 21h
cmp al, 13 ;When press enter on keyboard should terminate program
jmp L2
sub al, 48
mov bl, 10 ;◄■■ 9 + DOLLAR SIGN.
mul bl ;◄■■ AL * 10.
mov dx, offset week
add dx, ax ;◄■■ DX POINTS TO THE PROPER DAY.
mov ah, 9
int 21h ;◄■■ 21H, NOT 21.
jmp L1
L2: mov dx, offset bye
mov ah,9
int 21h
mov ax, 4c00h
int 21h
main endp
end
答案 0 :(得分：1)
我的代码中有一些错误，我用箭头指出（anf fixed），也乘以9（实际上它是10，因为每一天都以美元符号结束）：
.model small
.stack 100h ;◄■■ STACK!!!
.data
message db "Please enter a number between 0 and 6 : $"
week db "Sunday___$", "Monday___$", "Tuesday__$", "Wednesday$"
db "Thursday_$", "Friday___$", "Saturday_$"
.code ;◄■■ CODE!!!
main proc
mov ax,@data
mov ds, ax
mov ah,9
mov dx,OFFSET message
int 21h
mov ah,1
int 21h ;◄■■ NUMBER RETURNS IN AL.
sub al, 48 ;◄■■ CONVERT CHAR TO DIGIT.
mov bl, 10 ;◄■■ 9 + DOLLAR SIGN.
mul bl ;◄■■ AL * 10.
mov dx, offset week
add dx, ax ;◄■■ DX POINTS TO THE PROPER DAY.
mov ah, 9
int 21h ;◄■■ 21H, NOT 21.
mov ax, 4c00h
int 21h
main endp
end
编辑＃1：使用索引为每天的数组
.model small
.stack 100h
.data
message db "Please enter a number between 0 and 6 : $"
week db "Sunday$", "Monday$", "Tuesday$", "Wednesday$"
db "Thursday$", "Friday$", "Saturday$"
offs dw 0,7,14,22,32,41,48 ;◄■■ INDEXES OF DAYS.
.code
main proc
mov ax,@data
mov ds, ax
mov ah,9
mov dx,OFFSET message
int 21h
mov ah,1
int 21h
sub al, 48
xor ah, ah ;◄■■ CLEAR AH, SO AX=AL.
mov si, ax ;◄■■ TRANSFER NUMBER TO AN INDEX REGISTER.
shl si, 1 ;◄■■ SI*2, BECAUSE EACH INDEX IS DW.
add si, offset offs ;◄■■ INDEX OF DAY.
mov dx, offset week ;◄■■ DAYS OF WEEK.
add dx, [si] ;◄■■ THE DAY IN WEEK!
mov ah, 9
int 21h
mov ax, 4c00h
int 21h
main endp
end
编辑＃2：显示字母'A'到'L'的月份：
.model small
.stack 100h
.data
message db "Please enter a LETTER between 'A' and 'L' : $" ;◄■■■
week db ' January ',0dh,0ah,'$'
db 'february ',0dh,0ah,'$'
db ' March ',0dh,0ah,'$'
db ' April ',0dh,0ah,'$'
db ' May ',0dh,0ah,'$'
db ' June ',0dh,0ah,'$'
db ' July ',0dh,0ah,'$'
db ' August ',0dh,0ah,'$'
db 'September',0dh,0ah,'$'
db ' October ',0dh,0ah,'$'
db 'November ',0dh,0ah,'$'
db 'December ',0dh,0ah,'$'
bye db 0dh, 0ah, "BYE",0dh, 0ah, '$'
error_msg db 13,10,13,10,'Invalid char.',13,10,13,10,'$' ;◄■■■
.code
main proc
mov ax,@data
mov ds, ax
L1:
mov ah,9
mov dx,OFFSET message
int 21h
mov ah,1
int 21h
cmp al, 13 ;When press enter on keyboard should terminate program
je L2 ;◄■■■ JE = JUMP IF EQUAL (EQUAL TO 13).
;VALIDATE CHAR ◄■■■
cmp al, 'l'
ja error ;◄■■■ IF AL > 'l' (JA = JUMP IF ABOVE)
cmp al, 'A'
jb error ;◄■■■ IF AL < 'A' (JB = JUMP IF BELOW)
cmp al, 'L'
jbe fine ;◄■■■ IF AL <= 'L' (JBE = JUMP IF BELOW OR EQUAL)
cmp al, 'a'
jae fine ;◄■■■ IF AL >= 'a' (JAE = JUMP IF ABOVE OR EQUAL)
jmp error ;◄■■■ ANY OTHER CHAR IS ERROR.
fine:
;CHECK IF CHAR IS LOWERCASE ('a'..'z') OR UPPERCASE ('A'..'Z') ◄■■■
cmp al, 'Z' ;◄■■■
jb uppercase ;◄■■■ IF AL < 'Z'
sub al, 97 ;◄■■■ 'a' - 97 = 0.
jmp continue ;◄■■■ SKIP THE UPPERCASE BLOCK.
uppercase:
sub al, 65 ;◄■■■ 'A' - 65 = 0.
continue:
mov bl, 12 ;◄■■■ 9 + 0D + 0A + $ = 12.
mul bl ;◄■■■ AL * 12.
mov dx, offset week
add dx, ax ;◄■■■ DX POINTS TO THE PROPER MONTH.
mov ah, 9
int 21h ;◄■■■ DISPLAY MONTH.
jmp L1
error: ;◄■■■
mov ah, 9
mov dx, offset error_msg
int 21h
jmp L1
L2: mov dx, offset bye
mov ah,9
int 21h
mov ax, 4c00h
int 21h
main endp
end