Question

为什么在创建文件后，我的dosbox会自动关闭？我的代码有问题吗？

.model small
.stack 100h
.data
msg1    db      10, 13, 10, 13, "Please select an item:",0Dh,0Ah,0Dh,0Ah,09h
        db      "1- Create File",0Dh,0Ah,09h
        db      "2- show data",0Dh,0Ah,09h      
        db      "3- Exit",0Dh,0Ah,09h
        db      "Enter item number: " 
        db      '$'   
msg2    db      10,13,"Success Create$"
file    db      "test.txt"
handle  dw      ?
buffer  dw      10 dup (?)

.code
main proc 
    mov   ax,@data
    mov   ds,ax

ShowMenu:       
    lea     dx, msg1  
    mov     ah, 09h 
    int     21h     

    mov     ah, 01h ;get choice
    int     21h        

    cmp     al, "1"
    je      CreateFile
    cmp     al, "2"
    je      ShowData
    cmp     al, "3"
    jmp     Quit
    jl      ShowMenu

Quit: 
   mov   ah,4ch
   int   21h   

CreateFile:
mov ah,3ch ;create file
mov cx,0
lea dx,file;set file name
int 21h

lea dx,msg2
int 21h
jmp ShowMenu

ShowData:
mov ah,3dh ;open file
mov al,0   ;open as read only
lea dx,file
int 21h
mov handle,ax

;read one char
mov ah,3fh   ;service to read file
mov bx,handle
mov cx,1        ;how many byte to read
mov dx,buffer   ;where to store
int 21h

;close file
mov ah,3eh
mov bx,handle
int 21h

jmp ShowMenu


main endp
 end main

创建文本文件

Answer 1

在显示成功消息（comment by David Wohlferd）之前未设置功能代码09h的问题通常只会关闭程序，而不会 DOSBox仿真器。
通过创建文件得到的句柄通常会离开AH=0，随后将调用DOS终止函数。Terminate program

file    db      "test.txt"
handle  dw      ?

程序中的另一个问题是您忘记了将文件规范零终止：

 file    db      "test.txt", 0

垃圾文件规范可能会使DOSBox关闭！

因为handle变量定义为？（未初始化的内存），您可能很不幸，随后的字节不会恰好为零。

创建文本文件时关闭Dosbox

1 个答案: