尝试将“+”的输入与其 ASCII 值 43 进行比较

Question

我刚开始编写嵌入了代码的 posts，所以如果这看起来很糟糕，请让我休息一下，或者关于如何让它看起来更好的建议。 :)

我遇到的问题与标题所说的差不多。我正在为作业制作一个简单的计算器，我试图让程序比较输入的数学运算，例如 (+,-,*,/)。

*然后让 cmp 设置类似....

cmp 数学运算，43...*

*但是我无法让程序识别正确的东西。我将 post 以下代码的副本，但请记住，这只是一个草稿，只是试图找出一些想法。 *

感谢您的帮助！

; Author:  
; Date:    03/22/2022

.586
.MODEL FLAT

INCLUDE io.h            ; header file for input/output

.STACK 4096

.DATA
num1                   DWORD    ?
num2                   DWORD    ?
MathOper               DWORD    ?
result                 DWORD    20 DUP (?), 0
string                 BYTE     40 DUP (?), 0




Num1prm       BYTE  "Enter First Number", 0
Num2prm       BYTE  "Enter Second Number", 0
MathOPprm     BYTE  "Enter Math Operation (+,-,*,/)", 0
Resultprm     BYTE  "The Result is: ", 0
                            


.CODE
_MainProc PROC
loopy:
            input  Num1prm, string, 20
            atod    string
            mov     num1, eax
            
            input  MathOPprm, string, 20
            atod    string
            mov     MathOper, eax

            input  Num2prm, string, 20
            atod    string
            mov     num2, eax

            
            ;HAVING ISSUES GETTING THIS TO WORK
            cmp MathOper, 43
            jne SUBTRACTION
            call Addition
            dec ecx
            jnz loopy
           
           
           
            SUBTRACTION:           
            cmp MathOper, 45
            jne MULTIPLICATION
            call Subtraction

            MULTIPLICATION:
            cmp MathOper, 42
            jne DIVISION
            call Multiplication

            DIVISION:
            cmp MathOper, 47
            call Division
            cmp MathOper, 101
         
      
 endloopy:

            mov     eax, 0                   ; exit with return code 0
            ret
_MainProc ENDP
                                             ; end of source code


Addition PROC
        push    ebp
        mov     ebp, esp
        push    ebx
        
        mov     eax, num1
        mov     ebx, num2
        add     eax, ebx
        dtoa    result, eax

        output  Resultprm, result, 40
        pop     ebx
        pop     ebp

        ret
Addition ENDP

Subtraction PROC
        push    ebp
        mov     ebp, esp
        push    ebx
        
        mov     eax, num1
        mov     ebx, num2
        sub     eax, ebx
        dtoa    result, eax

        output  Resultprm, result, 40
        pop     ebx
        pop     ebp

        ret
Subtraction ENDP

Multiplication PROC
        push    ebp
        mov     ebp, esp
        push    ebx
        
        mov     eax, num1
        mov     ebx, num2
        mul     ebx
        dtoa    result, eax

        output  Resultprm, result, 40
        pop     ebx
        pop     ebp

        ret
Multiplication ENDP

Division PROC
        push    ebp
        mov     ebp, esp
        push    ebx
        
        mov     eax, num1
        mov     ebx, num2
        cdq
        idiv    ebx
        dtoa    result, eax

        output  Resultprm, result, 40
        pop     ebx
        pop     ebp

        ret
Division ENDP


END

Answer 1

您不想在读取输入后在 string 上调用 atod，因为它不是数字。
只需使用以下命令将字符串的第一个字符复制到 MathOper 中：

    movzx eax, [string]
    mov MathOper, eax

尝试将“+”的输入与其 ASCII 值 43 进行比较

Trying to compare input of '+' with its ASCII value of 43

x86

assembly

masm