I am trying to copy from one file to another. So if the user is prompted to enter a file name...FILE1 a saved string will be copied to a file then the user is prompted to enter a second file name...File2, the contents of file 1 is copied to file 2. I can find information on the read part but I'm not sure how to copy from 1 to the other???
.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
Ok, Jake, I have run you code and it works great. What you need is copy-paste some parts already there, and add three : open the first file, create another, and transfer data. I modify your code to achieve the goal, here it is, copy-paste it in your compiler and let me now if it worked :
.model small
.stack 100h
.data
handle dw ?
handle2 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).
filename2 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 13,10,"ENTER FILE NAME HERE: $"
prompt2 db 13,10,"ENTER A SECOND FILE NAME: $"
mess1 db ' I WIN! $'
buf db ?
.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 ;READ/WRITE MODE.
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
;CLOSE FILE.
mov ah, 3Eh ; close file
mov bx, handle ; which file
int 21h
;OPEN FILE TO READ FROM IT.
mov ah, 3DH
mov al, 0 ;READ MODE.
mov dx, offset filename + 2
int 21h
mov handle, ax ; save file handle
;DISPLAY MESSAGE FOR SECOND FILE.
lea dx, prompt2 ; load and print the string PROMPT
mov ah, 9
int 21h
;CAPTURE FILENAME FROM KEYBOARD.
mov ah, 0Ah
mov dx, offset filename2 ;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 filename2 + 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 ;READ/WRITE MODE.
mov dx, offset filename2 + 2 ;CHARACTERS START AT BYTE 2.
int 21h
jc failed ; end program if failed
mov handle2, ax ; save file handle
;READ ALL BYTES FROM FIRST FILE AND WRITE THEM TO SECOND FILE.
reading:
;READ ONE BYTE.
mov ah, 3FH
mov bx, handle
mov cx, 1 ;HOW MANY BYTES TO READ.
mov dx, offset buf ;THE BYTE WILL BE STORED HERE.
int 21h ;NUMBER OF BYTES READ RETURNS IN AX.
;CHECK EOF (END OF FILE).
cmp ax, 0 ;IF AX == 0 THEN EOF.
je eof
;WRITE BYTE TO THE SECOND FILE.
mov ah, 40h ; write to
mov bx, handle2 ; file
mov dx, offset buf ; where to find data to write
mov cx, 1 ;LENGTH OF STRING IN CX.
int 21h
jmp reading ;REPEAT PROCESS.
eof:
;CLOSE FILES.
mov ah, 3Eh ; close file
mov bx, handle ; which file
int 21h
mov ah, 3Eh ; close file
mov bx, handle2 ; which file
int 21h
failed:
mov ah, 4ch
int 21h
end main
By the way : reading one byte at a time is not efficient, actually, if the file is not too big, it's possible to read it all at once (that's efficient). Another option is to read bytes two by two, or ten by ten, just take care of the last read because maybe will read less than 10 bytes.
来源：https://stackoverflow.com/questions/29571779/how-to-copy-from-one-file-to-another