制作 --- 的字符串，末尾为 0

Question

我不能使用这个声明，因为 selectedWords 可以是任何字符串。

.DATA
guessWords BYTE SIZEOF selectedWords DUP ('-'), 0  

所以我尝试这样做：

;Wordls what we select by rundom code
selectedWords BYTE ?
lengthSelectedWorld DWORD ?

;Letter what we guess, input from keyboard
guessLetter BYTE ?
guessWords BYTE ? 
;Letter what are unknows, change with - 
letterUnknown BYTE "-", 0

我已经写了这个函数

make_array1 PROC     

    mov  edx,OFFSET selectedWords
    call StrLength
    mov  lengthSelectedWorld,eax
    mov  lengthSelectedWorld1 ,eax
    inc  lengthSelectedWorld

    loop_add_more:
        cmp lengthSelectedWorld, 1 
        je done
        dec lengthSelectedWorld       
        mov eax, '-'
        mov ecx, lengthSelectedWorld1
        mov edi, offset guessWords
        rep stosw

        mov edx, offset guessWords
        call WriteString
        call Crlf ;stampamo enter novi red

        jmp loop_add_more    

    done:
        mov eax, '0'
        mov ecx, lengthSelectedWorld1
        mov edi, offset guessWords
        rep stosw

        mov edx, offset guessWords
        call WriteString
        call Crlf ;stampamo enter novi red

        ret

make_array1 ENDP  

但是在这个函数之后，我得到了guessWords什么是字符串-------并且and上没有0。那么如何使字符串guessWords=--------0？

由于代码中的一些其他比较，字符串末尾有 0 对我来说很重要..

Answer 1

selectedWords BYTE ? 只为 selectedWords 保留一个字节。 guessWords BYTE ? 也有同样的问题。不要像新手一样玩动态分配的内存。而是保留在任何情况下都足够的空间：guessWords BYTE 50 DUP (?)。问号表示 MASM 可以决定将其视为未初始化的内存（不存储在 .exe 文件中，而是在程序启动时分配）。

STOSW 存储一个 WORD（= 两个字符）。但是 Irvine 的 StrLength 返回字符串的字节数。请改用STOSB。在STOSB 之后，EDI 指向最后存储的AL 之后的字符。你可以在那里存储一个空值。想看的话，暂时把0改成'0'吧。

INCLUDE Irvine32.inc

.DATA

;Wordls what we select by rundom code
selectedWords BYTE "WEIGHTLIFTING", 0
lengthSelectedWord DWORD ?

;Letter what we guess, input from keyboard
guessLetter BYTE ?
guessWords BYTE 50 DUP (?)

;Letter what are unknows, change with -
letterUnknown BYTE "-", 0

.CODE

make_array1 PROC

    mov  edx,OFFSET selectedWords
    call StrLength                      ; Irvine32: Length of a null-terminated string pointed to by EDX
    mov  lengthSelectedWord,eax

    loop_add_more:
        mov al, '-'                     ; Default charcter for guessWords
        mov ecx, lengthSelectedWord     ; REP counter
        mov edi, offset guessWords      ; Destination
        rep stosb                       ; Build guessWords
        mov BYTE PTR [edi], 0           ; Store the null termination

        mov edx, offset guessWords
        call WriteString                ; Irvine32: write a string pointed to by EDX
        call Crlf                       ; Irvine32: new line

        ret

make_array1 ENDP

main PROC

    call make_array1
    exit                                ; Irvine32: ExitProcess

main ENDP

END main