问题
I am having trouble printing "I WIN!" to a file 100 times. I can get it to print but it prints with garble can someone please point out what I am doing wrong? I need the code to print without any garble with "I WIN!" one after the other.
.model small
.stack 100h
.data
handle dw ?
filename db "myfile.txt", 0
prompt1 db "ENTER FILE NAME HERE: $"
mess1 db ' I WIN! $'
.code
main:
mov ax, @data ; set up addressability of data
mov ds, ax
lea dx, prompt1 ; load and print the string PROMPT
mov ah, 9
int 21h
mov ah, 3ch ; dos service to create file
mov cx, 0
mov dx, offset filename
int 21h
jc failed ; end program if failed
mov handle, ax ; save file handle
mov cx, 100 ; number of bytes to write
PL:
mov ah, 40h ; write to
mov bx, handle ; file
mov dx, offset mess1 ; where to find data to write
dec cx
int 21h
jnz PL
mov ah, 3Eh ; close file
mov bx, handle ; which file
int 21h
failed:
mov ah, 4ch
int 21h
end main
回答1:
The problem is that the block of code to write on file requires the length of the string in CX, and you are already using CX as the loop counter, so, I fixed your code to use DI instead of CX, like this :
.model small
.stack 100h
.data
handle dw ?
filename db 26 ;MAX NUMBER OF CHARACTERS ALLOWED (25).
db ? ;LENGTH (NUMBER OF CHARACTERS ENTERED BY USER).
db 26 dup(0) ;CHARACTERS ENTERED BY USER. END WITH CHR(13).
prompt1 db "ENTER FILE NAME HERE: $"
mess1 db ' I WIN! $'
.code
main:
mov ax, @data ; set up addressability of data
mov ds, ax
;DISPLAY MESSAGE.
lea dx, prompt1 ; load and print the string PROMPT
mov ah, 9
int 21h
;CAPTURE FILENAME FROM KEYBOARD.
mov ah, 0Ah
mov dx, offset filename ;THIS VARIABLE REQUIRES THE 3-DB FORMAT.
int 21h
;CAPTURED STRING ENDS WITH CHR(13), BUT TO CREATE FILE WE NEED
;THE FILENAME TO END WITH CHR(0), SO LET'S CHANGE IT.
mov si, offset filename + 1 ;NUMBER OF CHARACTERS ENTERED.
mov cl, [ si ] ;MOVE LENGTH TO CL.
mov ch, 0 ;CLEAR CH TO USE CX.
inc cx ;TO REACH CHR(13).
add si, cx ;NOW SI POINTS TO CHR(13).
mov al, 0
mov [ si ], al ;REPLACE CHR(13) BY 0.
;CREATE FILE.
mov ah, 3ch ; dos service to create file
mov cx, 0
mov dx, offset filename + 2 ;CHARACTERS START AT BYTE 2.
int 21h
jc failed ; end program if failed
mov handle, ax ; save file handle
mov DI, 100 ;CAN'T USE CX BECAUSE WE NEED IT TO WRITE TO FILE.
PL:
;WRITE STRING ON FILE.
mov ah, 40h ; write to
mov bx, handle ; file
mov dx, offset mess1 ; where to find data to write
mov cx, 7 ;LENGTH OF STRING IN CX.
int 21h
DEC DI ;DECREASE COUNTER.
jnz PL
mov ah, 3Eh ; close file
mov bx, handle ; which file
int 21h
failed:
mov ah, 4ch
int 21h
end main
I have edited the code to capture filename from keyboard. Explanation : to capture strings from keyboard we use service 0AH, which requires a variable with the 3-DB format : one DB for the max number of characters allowed (plus 1), another DB for the length, and a third DB for the characters themselves. If we want to capture 25 must specify 26 because the capture ends with chr(13).
To create the file the filename must end with chr(0), so we have to find chr(13) and replace it with chr(0).
来源：https://stackoverflow.com/questions/29569269/writing-a-string-to-a-file-100-times-in-assembly