Print Page - Question about if statements

Title: Question about if statements
Post by: bcddd214 on May 06, 2011, 01:03:26 AM

My edx is recieving garbage instead of the inputted value.

I am just doing a small comparison program where the user inputs two numbers and is displayed a message of "> or < or =".

*******code*******************
TITLE         GreaterThan

INCLUDE IRVINE32.inc
.code
X BYTE ?
Y BYTE ?
Z BYTE ?
mes1 BYTE "Enter X: ",0
mes2 BYTE "Enter Y: ",0
mes3 byte " is > than ",0
mes4 byte " is < than ",0
mes5 byte " is = to ",0

.code
MAIN PROC
   mov al, 0
   mov edx, offset mes1
   call writestring
   call crlf
   call readint
   mov edx,offset mes2
   call writestring
   call crlf
   call readint
   call DumpRegs

mov al,x
.if al>Y
mov al,X
mov edx, offset mes3
call writedec
call writestring
mov al,Y
call writedec
call crlf
.elseif y>al
    mov al,Y
mov edx, offset mes4
call writedec
call writestring
mov al,X
call writedec
call crlf
    .else
     mov al,Y
mov edx, offset mes5
call writedec
call writestring
mov al,X
call writedec
call crlf
.endif

MAIN ENDP
END MAIN

Title: Re: Question about if statements
Post by: bcddd214 on May 06, 2011, 01:18:26 AM

Now I am getting a problem with last line statement. The statement that involves the "END MAIN", sorry for the noob question...

***********************Code*********************************

TITLE         GreaterThan

INCLUDE IRVINE32.inc
.code
X BYTE ?
Y BYTE ?
Z BYTE ?
mes1 BYTE "Enter X: ",0
mes2 BYTE "Enter Y: ",0
mes3 byte " is > than ",0
mes4 byte " is < than ",0
mes5 byte " is = to ",0

.code
main PROC
   mov al, 0
   mov edx, offset mes1
   call writestring
   call crlf
   call readint
   mov edx,offset mes2
   call writestring
   call crlf
   call readint
   call NumberH
   call DumpRegs
main ENDP

NumberH PROC
mov al,x
.if al>Y
mov al,X
mov edx, offset mes3
call writedec
call writestring
mov al,Y
call writedec
call crlf
     .elseif y>al
    mov al,Y
mov edx, offset mes4
call writedec
call writestring
mov al,X
call writedec
call crlf
    .else
     mov al,Y
mov edx, offset mes5
call writedec
call writestring
mov al,X
call writedec
call crlf
    .endif
ret
END NumberH
EXIT
END main

Title: Re: Question about if statements
Post by: dedndave on May 06, 2011, 04:00:10 AM

Code Select

END NumberH
EXIT
END main

:bg

Code Select

;----------------------

main PROC
;code
exit
main ENDP

;----------------------

NumberH PROC
;code
ret
NumberH ENDP

;----------------------

END main

Title: Re: Question about if statements
Post by: RuiLoureiro on May 06, 2011, 03:31:34 PM

You need this:

X dd ? ;<<<<<<<<< DWORD not byte ! ...
Y dd ?
Z dd ?

main PROC
mov al, 0
mov edx, offset mes1
call writestring
call crlf
call readint
mov X, eax ;<<<<<<<<<<<<<<<<<<<<<<<<

mov edx,offset mes2
call writestring
call crlf
call readint
mov Y, eax ;<<<<<<<<<<<<<<<<<<<<<<<<

call NumberH
call DumpRegs
main ENDP

and changes in NumberH

Title: Re: Question about if statements
Post by: dedndave on May 06, 2011, 04:40:14 PM

Rui - don't forget "exit" at the end of main :P

Title: Re: Question about if statements
Post by: mineiro on May 06, 2011, 04:47:51 PM

Your EXIT is in wrong place and look the diference betwen ENDP and END.
Irvine uses dword to ReadInt procedure, and you are not saving the returned value in some variable like Sr RuiLoureiro says.

Code Select

INCLUDE IRVINE32.inc
.code                 ;here is .data and not .code
X BYTE ?

Code Select


.code
MAIN PROC
   mov al, 0    ;you don't need this line

In your NumberH procedure, you are inserting so much code that do the same thing, you can write it smaller, so your final program stay smaller.
To compare numbers that are the same using IF statement, you can use a double equal signal "==". Like "If eax == Y".

Code Select


NumberH PROC
   mov	eax,X
   .if eax>Y
     mov edx, offset mes3
    .elseif eax<Y
     mov edx, offset mes4
    .else		;elseif eax==Y
     mov edx, offset mes5
    .endif
     call writedec
     call writestring
     mov eax,Y
     call writedec
     call crlf
ret
NumberH ENDP

Title: Re: Question about if statements
Post by: RuiLoureiro on May 06, 2011, 04:57:31 PM

Quote from: dedndave on May 06, 2011, 04:40:14 PM
Rui - don't forget "exit" at the end of main :P

Yes dave ! He need to learn ... :green2

Dont forget call WaitMsg before EXIT

Title: Re: Question about if statements
Post by: bcddd214 on May 10, 2011, 12:22:07 AM

Quote from: dedndave on May 06, 2011, 04:00:10 AM
:(
Code Select Expand
END NumberH EXIT END main

:bg
Code Select Expand
;---------------------- main PROC ;code exit main ENDP ;---------------------- NumberH PROC ;code ret NumberH ENDP ;---------------------- END main

********************************
Assembling: greater-than1.asm
greater-than1.asm(56) : error A2005: symbol redefinition : main
greater-than1.asm(59) : fatal error A1010: unmatched block nesting : main

Title: Re: Question about if statements
Post by: dedndave on May 10, 2011, 12:28:31 AM

take the first section out :bg

bad stuff.....

Code Select

END NumberH
EXIT
END main

remove that part

good stuff.....

Code Select

;----------------------

main PROC
;code
exit
main ENDP

;----------------------

NumberH PROC
;code
ret
NumberH ENDP

;----------------------

END main

Title: Re: Question about if statements
Post by: bcddd214 on May 10, 2011, 12:35:26 AM

I apologize for the very 'un thought out' question earlier.
my only issues is not being able to access the variables in the NumberH PROC.

This has to do with main I am sure. Can I just use jmp to get past this the easy way?

***********************code***************************
TITLE GreaterThan

INCLUDE IRVINE32.inc
.data
X BYTE ?
Y BYTE ?
Z BYTE ?
mes1 BYTE "Enter X: ",0
mes2 BYTE "Enter Y: ",0
mes3 byte " is > than ",0
mes4 byte " is < than ",0
mes5 byte " is = to ",0

.code
main PROC
; mov al, 0
mov edx, offset mes1
call writestring
call crlf
call readint
mov edx,offset mes2
call writestring
call crlf
call readint
call NumberH
call DumpRegs
exit
main ENDP

NumberH PROC
mov eax,X
.if eax>Y
mov edx, offset mes3
.elseif eax<Y
mov edx, offset mes4
.else
mov edx, offset mes5
.endif
call writedec
call writestring
mov eax,Y
call writedec
call crlf
ret
NumberH ENDP

END main

Title: Re: Question about if statements
Post by: dedndave on May 10, 2011, 12:40:00 AM

ok
you have defined X, Y, and Z as BYTE's
then, you try to MOV them into and compare them with dword registers
the best fix is to make them DWORD's instead of BYTE's

Code Select

X dd ?
Y dd ?
Z dd ?

Title: Re: Question about if statements
Post by: bcddd214 on May 10, 2011, 07:28:26 PM

Looking better but she still does not want to actually make the comparison?

************code********************
TITLE GreaterThan

INCLUDE IRVINE32.inc
.data
X dword ?
Y dword ?
Z dword ?
mes1 BYTE "Enter X: ",0
mes2 BYTE "Enter Y: ",0
mes3 byte " is > than ",0
mes4 byte " is < than ",0
mes5 byte " is = to ",0

.code
main PROC
; mov al, 0
mov edx, offset mes1
call writestring
call crlf
call readint
mov edx,offset mes2
call writestring
call crlf
call readint
call NumberH
call DumpRegs
exit
main ENDP

NumberH PROC
mov eax,X
.if eax>=Y
mov edx, offset mes3
.elseif eax<=Y
mov edx, offset mes4
.else
mov edx, offset mes5
.endif
call writedec
call writestring
mov eax,Y
call writedec
call crlf
ret
NumberH ENDP

END main

Title: Re: Question about if statements
Post by: dedndave on May 10, 2011, 08:52:12 PM

:bg
after ReadInt, don't you want to store the user-entered values ?

Code Select

        mov     edx, offset mes1
        call    WriteString
        call    CrLf
        call    ReadInt
        mov     X,eax            ;<----
        mov     edx,offset mes2
        call    WriteString
        call    CrLf
        call    ReadInt
        mov     Y,eax            ;<----

also, i think this means "equal or greater than"

Code Select

.if eax>=Y
you probably just want "greater than"

Code Select

.if eax>Y

Code Select

.elseif eax<=Y
and for that one, "less than"

Code Select

.elseif eax<Y

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General Forums => The Campus => Topic started by: bcddd214 on May 06, 2011, 01:03:26 AM