how can i make my prog. accepts only 'y' &'n' char

[stapo34]

how can i make my prog. accepts only 'y' &'n' char?

i really dont know what to do.



any help much appreciated.

[BogdanOntanu]

Do not double post, be patient and explain better your problem in such a way as more people can understand what you are trying to do and in what context and maybe this way you will get more answers faster.

You give too little context ... is this a windows or a dos application? is this a GUI or a console application? 32 bits or 16 bits or 64 bits?

Basically:
1) read key from user
2) compare key with "y"
3) if compare is equal then execute code for this case
4) if not then compare key with "n"
5) if compare is equal then execute code for this case
6) else emit an error message because key is not "y" or "n"

The exact specifics depend a lot on you giving more info...

And BTW we do not solve homework, this is a rule here

[raymond]

REMINDER

If your program is to be used by other than yourself alone, don't repeat the same error as some programmers used to do. Also check if the input is one of the upper case letters in addition to the lower case letters. There's nothing more aggravating than pressing "Y" (or "N") repeatedly and nothing happens. :boohoo:

[dedndave]

easy way is to simply force upper or lower case

[oex]

There's nothing more aggravating than pressing "Y" (or "N") repeatedly and nothing happens. :boohoo:

cmp al, 'Y'
je RTFS
cmp al, 'N'
je RTFS

RTFS:
print "RTFS.... Press 'y' or 'n'.... I dont know why I bother sometimes.... I might as well do it all myself and tell you when I'm done.... You dont listen to a word I say...."

[dedndave]

Code Select Expand

and al,0DFh ;force upper case
cmp al, 'Y'
je RTFS
cmp al, 'N'
je RTFS

[donkey]

If you are using a GUI application and the program stops for user input you can use a message box with the MB_YESNO style, it will only display a yes and no button and will return IDYES or IDNO as results (IDYES being the default).

Edgar

[ToutEnMasm]

You can also intercept the message loop and:

.elseif uMsg == WM_CHAR         ;keyboard
      .if wParam == "Y" || wParam == "y"

for a control , you have to use this

   INVOKE     SetWindowLong, Hredit, GWL_WNDPROC, EventRichEdit

Then create "EventRichEdit" the proc for events

[jj2007]

Fascinating topic... 154 views and 8 answers so far :wink

Code Select Expand

include \masm32\include\masm32rt.inc

.code
AppName db "Masm32:", 0

start:
@@: print "Press y[es] or n[o]", 13, 10
getkey
or al, 32  ; lowercase
cmp al, "y"
je PressedYes
cmp al, "n"
jne @B

PressedNo:
inkey "Oh no..."
exit
PressedYes:
inkey "Oh yes..."
exit

end start


[ToutEnMasm]

Fascinating topic... 154 views and 8 answers so far

Perhaps if the author can say he want to use this under:
                    Windows
                    Dos
                    In a windows or without window
Answers will be less numerous.

[Vortex]

Hi stapo34,

Here is a quick example for you :

Code Select Expand

.386
.model flat,stdcall
option casemap:none

include     \masm32\include\windows.inc
include     \masm32\include\kernel32.inc
include     \masm32\include\user32.inc

includelib  \masm32\lib\kernel32.lib
includelib  \masm32\lib\user32.lib


.data

msgtable    dd OFFSET yes , OFFSET no
text1       db 'Hit yes or no',0
capt        db 'Hello',0
yes         db 'You pressed yes',0
no          db 'You pressed no',0



.code

start:

    invoke  MessageBox,0,ADDR text1,ADDR capt,MB_YESNO

    shl     eax,2       ; eax = eax * 4

                        ; IDYES = 6   ,   IDNO = 7

    add     eax,OFFSET msgtable - 4 * IDYES

    invoke  MessageBox,0,DWORD PTR [eax],ADDR capt,MB_OK
         
    invoke  ExitProcess,0

END start