在我的大学里，我接到了以下任务：逐个字符地比较两个文本文件的内容。仅将第一个文件中的那些字符及其在文件中的位置编号与第二个文件中的相应字符不匹配的字符写入新的文本文件。使用 TASM 汇编程序。 好吧，我编写了程序，通过 Turbo 汇编程序运行了它，但没有任何内容写入 output.txt 文件。所有文件都在同一个目录中。 file1.txt abobabiba1 的内容，file2.txt abobapipa1 的内容。 理论上，像这样的东西应该写入文件
5 7
bb
.model large
.stack 1000h
.data
infile1 db "file1.txt", 0
infile2 db "file2.txt", 0
outfile db "output.txt", 0
buffer1 db 1000h dup(?)
buffer2 db 1000h dup(?)
outfile_char db 0
position db 0
end_of_file db 0
.code
main proc
; open the first input file
mov ah, 3dh
mov al, 0
lea dx, infile1
int 21h
mov bx, ax ; bx contains the first file descriptor
; open second input file
mov ah, 3dh
mov al, 0
lea dx, infile2
int 21h
mov cx, ax ; cx contains the second file descriptor
; create output file
mov ah, 3ch
mov al, 0
lea dx, outfile
int 21h
mov dx, ax ; dx contains the output file descriptor
; read the contents of the first file into buffer1
mov ah, 3fh
mov bx, ax
lea dx, buffer1
mov cx, 1000h
int 21h
; read the contents of the first file into buffer2
mov ah, 3fh
mov bx, cx
lea dx, buffer2
mov cx, 1000h
int 21h
; compare the contents of the buffers character by character
mov si, offset buffer1
mov di, offset buffer2
mov cx, 1000h
mov position, 0
loop_start:
mov al, [si]
mov bl, [di]
cmp al, bl
je skip
; set the file pointer to the beginning of the file
mov ah, 42h
mov al, 0
mov bx, dx
int 21h
; write information to the output file
mov ah, 02h
mov dl, al
mov ah, 40h
mov bx, dx
mov cx, 1
mov dx, offset outfile_char
int 21h
mov ah, 02h
mov dl, position
add dl, '0'
mov ah, 40h
mov bx, dx
mov cx, 1
mov dx, offset outfile_char
int 21h
mov ah, 40h
mov bx, dx
mov cx, 1000h
lea dx, buffer1
int 21h
mov ah, 40h
mov bx, dx
mov cx, 1000h
lea dx, buffer2
int 21h
skip:
; increment the position and move on to the next character
inc si
inc di
inc position
; check for end of file
cmp position, 10h
jne loop_start
; close the output file
mov ah, 3eh
mov bx,dx
int 21h
; close the second input file
mov ah, 3eh
mov bx, cx
int 21h
; close the first input file
mov ah, 3eh
mov bx, ax
int 21h
; we complete the program
mov ah, 4ch
int 21h
main endp
end main
你确定DS指向你的
.data.code您的程序中最重要的错误是您将多个寄存器用于多个用途，并且您没有采取预防措施，例如在堆栈上保留它们的预先存在的值。
另一种方法是将一些数据存储在基于内存的变量中。你绝对应该为你的文件句柄选择这个，就像在下一个代码中一样：
; open the first input file
mov ah, 3dh
mov al, 0
lea dx, infile1
int 21h
jc SomeError
mov handle1, ax ; the first file descriptor
; open second input file
mov ah, 3dh
mov al, 0
lea dx, infile2
int 21h
jc SomeError
mov handle2, ax ; the second file descriptor
; create output file
mov ah, 3ch
mov al, 0 <<<< THIS IS AN ERROR: NEEDS TO BE CX=0
lea dx, outfile
int 21h
jc SomeError
mov handle3, ax ; the output file descriptor
; read the contents of the first file into buffer1
mov ah, 3fh
mov bx, handle1
mov cx, 16
lea dx, buffer1
int 21h
jc SomeError
; read the contents of the first file into buffer2
mov ah, 3fh
mov bx, handle2
mov cx, 16
lea dx, buffer2
int 21h
jc SomeError
...
; close the output file
mov ah, 3eh
mov bx, handle3
int 21h
; close the second input file
mov ah, 3eh
mov bx, handle2
int 21h
; close the first input file
mov ah, 3eh
mov bx, handle1
int 21h
; set the file pointer to the beginning of the file mov ah, 42h mov al, 0 mov bx, dx int 21h
在比较缓冲区的程序中间部分，您还试图重置输出文件指针。我说“尝试”是因为您没有正确设置参数！但是为什么你需要重置任何东西？文件创建后，文件指针已经在开头。此外，每次查找时重置文件指针将继续覆盖以前的结果！
mov ah, 02h mov dl, al ... mov ah, 02h mov dl, position add dl, '0'
在“将信息写入输出文件”的部分，您将字符输出到屏幕（但不完整）与缓冲区输出到文件混合。如果屏幕上的字符输出是出于测试目的，那么请在文本中用适当的注释记录下来，否则请删除这些行，因为它们非常令人不安。
这就是你输出字符的方式。请注意，该字符位于地址 SI:
; write information to the output file
mov ah, 40h
mov bx, handle3
mov cx, 1
mov dx, si
int 21h
jc SomeError
在这里你可以学习如何写职位：
mov al, position ; [0,9] will work fine
add al, '0'
mov outfile_char, al
mov ah, 40h
mov bx, handle3
mov cx, 1
mov dx, offset outfile_char
int 21h