计算器实现简单的加减乘除运算（小于65536的正数）
①从键盘输入算数的等式
②不接受复合算数如3 5*7
③按‘=’号输出结果
④按‘C’号作为CLEAR清零
程序分为输入模块，判断模块，计算模块，输出模块。
其他：增加了一些特性
①能够得出两个正数相减得到的负数
②能够计算除法中的余数
③比较美观
代码过长由于增加了一些特性
Assembly (x86)
代码语言：txt复制DATA SEGMENT
divisors DW 10000, 1000, 100, 10, 1
results DB 0,0,0,0,0,"$" ;存放五位数ASCII码
data ends
STACK SEGMENT
STACK ENDS
CODE SEGMENT
ASSUME CS:CODE
MAIN PROC FAR
MOV AX,DATA
MOV DS,AX
NOW:
MOV AX,0
CALL INPUT
PUSH BX
;------------------------
CMP AL,' '
JZ PLUS
CMP AL,'-'
JZ MINUS
CMP AL,'*'
JZ BY
CMP AL,'/'
JZ DIVD
PLUS:
CALL INPUT
POP AX
ADD AX,BX
JMP NEXT
MINUS:
CALL INPUT
POP AX
CMP AX,BX
JL LESS
SUB AX,BX
JMP NEXT
LESS:
SUB AX,BX
NEG AX
PUSH AX
MOV DL,'-'
MOV AH,02H
INT 21H
POP AX
JMP NEXT
BY:
CALL INPUT
POP AX
MUL BX
JMP NEXT
DIVD:
CALL INPUT
POP AX
CMP AX,BX
JL LESS2
DIV BX
JMP NEXT
LESS2:
PUSH AX
MOV DL,30H
MOV AH,02H
INT 21H
MOV DL,'~'
MOV AH,02H
INT 21H
POP AX
JMP NEXT
;---------------------------
NEXT:
CALL OUTPUT
JMP NOW
MOV AH,4CH
INT 21H
RET
MAIN ENDP
;---------------------
INPUT PROC NEAR
MOV BX,0
NUM:
MOV AH,1
INT 21H
CMP AL,'C'
JZ CLEAR
CMP AL,' '
JZ EXIT
CMP AL,'-'
JZ EXIT
CMP AL,'*'
JZ EXIT
CMP AL,'/'
JZ EXIT
SUB AL,30H
JL EXIT
CMP AL,9
JG EXIT
CBW
XCHG AX,BX
MOV CX,10
MUL CX
XCHG AX,BX
ADD BX,AX
JMP NUM
CLEAR:
MOV DL,0DH
MOV AH,2
INT 21H
MOV DL,0AH
MOV AH,2
INT 21H
MOV AX,0
MOV BX,0
JMP NUM
EXIT:RET
INPUT ENDP
;----------------------
OUTPUT PROC NEAR
mov si, offset divisors
mov di, offset results
mov cx,5
CAL:
mov dx,0
div word ptr [si]
add al,30H
mov byte ptr [di],al
inc di
add si,2
mov ax,dx
LOOP CAL
mov cx,4
mov di, offset results
NZ:
cmp byte ptr [di],'0'
jne print
inc di
loop NZ
print:
mov dx,di
MOV AH,9
INT 21H
RET
OUTPUT ENDP
;---------------------
CODE ENDS
END MAIN
