您可以替换?"之后的所有内容.以零表示，因此?"之后的所有字符被删除":

You can replace everything after the "?" by zeroes, so all the characters after "?" are been "removed" :

INCLUDE Irvine32.inc

.data
source BYTE "Is this a string? Enter y for yes, and n for no",0

.code
main PROC

mov edi, OFFSET source
mov al, '?'                  ; search for ?
mov ecx, LENGTHOF source
cld
repne scasb       ; repeat while not equal
jnz quit
dec edi           ; edi points to ?

;REPLACE ALL CHARACTERS BY "AL" (ZERO) STARTING WHERE "EDI" WAS AND
;FINISH WHEN "ECX" == 0.
mov al, 0         ;<=====================================
repne stosb       ;<=====================================

end main

请注意，搜索?"后，我们如何使用EDI和ECX的值.

Notice how we are using the values that EDI and ECX have after searching for "?".