How to compare inputs and check if a number is negative, positive or zero
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0
down vote
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I wrote the initial code for this problem but I want to be able to take -1 as an input. Right now it takes only one input 1 or - and then shows the result.
I'm a novice when it comes to assembly language and emu8086 so it would really help me out if someone could help me to solve this problem.
Here's the code so far:
.model small
.stack 100h
.data
msg db 0ah,0dh,'negative$'
msg1 db 0ah,0dh,'positive$'
msg2 db 0ah,0dh, 'zero$'
.code
main proc
mov ax,@data
mov ds,ax
mov ah,1
int 21h
mov bl,al
mov cl,30h
cmp bl,cl
jl negative
je zero
jg positive
negative:
lea dx,msg
mov ah,9
int 21h
jmp END
zero:
lea dx,msg2
mov ah,9
int 21h
jmp END
positive:
lea dx,msg1
mov ah,9
int 21h
END:
mov ah,4ch
int 21h
main endp
end main
assembly emu8086
edited Nov 9 at 13:56
fewlinesofcode
1,930515
asked Nov 9 at 9:50
Fayyadh Kabir
1
add a comment |
up vote
0
down vote
favorite
I wrote the initial code for this problem but I want to be able to take -1 as an input. Right now it takes only one input 1 or - and then shows the result.
I'm a novice when it comes to assembly language and emu8086 so it would really help me out if someone could help me to solve this problem.
Here's the code so far:
.model small
.stack 100h
.data
msg db 0ah,0dh,'negative$'
msg1 db 0ah,0dh,'positive$'
msg2 db 0ah,0dh, 'zero$'
.code
main proc
mov ax,@data
mov ds,ax
mov ah,1
int 21h
mov bl,al
mov cl,30h
cmp bl,cl
jl negative
je zero
jg positive
negative:
lea dx,msg
mov ah,9
int 21h
jmp END
zero:
lea dx,msg2
mov ah,9
int 21h
jmp END
positive:
lea dx,msg1
mov ah,9
int 21h
END:
mov ah,4ch
int 21h
main endp
end main
assembly emu8086
edited Nov 9 at 13:56
fewlinesofcode
1,930515
asked Nov 9 at 9:50
Fayyadh Kabir
1
keep in mind theint 21h, ah=1does return "characters" (or zero when extended scan code will be returned upon next call), not integers, so entering "-1" as user, when handled by this service, will need two calls, and values 45 (ASCII encoding for '-') and 49 (ASCII encoding for '1') will be returned. There are no DOS or BIOS services in PC to input integers, so you are on the correct path, but you must write your own code to handle multi-character input, and convert it from string into number (or you can use some library, not sure what emu8086 has in offer by default).
– Ped7g
Nov 9 at 13:05
(as now you are only printing negative/zero/positive, you don't even need to convert the string into integer, your current code is quite OK, it just needs some way to know how many chars it should read (if only single digit input values are allowed, then you need to read one or two chars, depending if "-" was used... also it would be nice then to support "+", i.e. "+4" as valid input))
– Ped7g
Nov 9 at 13:06
add a comment |
up vote
0
down vote
favorite
up vote
0
down vote
favorite
I wrote the initial code for this problem but I want to be able to take -1 as an input. Right now it takes only one input 1 or - and then shows the result.
I'm a novice when it comes to assembly language and emu8086 so it would really help me out if someone could help me to solve this problem.
Here's the code so far:
.model small
.stack 100h
.data
msg db 0ah,0dh,'negative$'
msg1 db 0ah,0dh,'positive$'
msg2 db 0ah,0dh, 'zero$'
.code
main proc
mov ax,@data
mov ds,ax
mov ah,1
int 21h
mov bl,al
mov cl,30h
cmp bl,cl
jl negative
je zero
jg positive
negative:
lea dx,msg
mov ah,9
int 21h
jmp END
zero:
lea dx,msg2
mov ah,9
int 21h
jmp END
positive:
lea dx,msg1
mov ah,9
int 21h
END:
mov ah,4ch
int 21h
main endp
end main
assembly emu8086
edited Nov 9 at 13:56
fewlinesofcode
1,930515
asked Nov 9 at 9:50
Fayyadh Kabir
1
I wrote the initial code for this problem but I want to be able to take -1 as an input. Right now it takes only one input 1 or - and then shows the result.
I'm a novice when it comes to assembly language and emu8086 so it would really help me out if someone could help me to solve this problem.
Here's the code so far:
.model small
.stack 100h
.data
msg db 0ah,0dh,'negative$'
msg1 db 0ah,0dh,'positive$'
msg2 db 0ah,0dh, 'zero$'
.code
main proc
mov ax,@data
mov ds,ax
mov ah,1
int 21h
mov bl,al
mov cl,30h
cmp bl,cl
jl negative
je zero
jg positive
negative:
lea dx,msg
mov ah,9
int 21h
jmp END
zero:
lea dx,msg2
mov ah,9
int 21h
jmp END
positive:
lea dx,msg1
mov ah,9
int 21h
END:
mov ah,4ch
int 21h
main endp
end main
assembly emu8086
assembly emu8086
edited Nov 9 at 13:56
fewlinesofcode
1,930515
asked Nov 9 at 9:50
Fayyadh Kabir
1
edited Nov 9 at 13:56
fewlinesofcode
1,930515
asked Nov 9 at 9:50
Fayyadh Kabir
1
edited Nov 9 at 13:56
fewlinesofcode
1,930515
edited Nov 9 at 13:56
fewlinesofcode
1,930515
edited Nov 9 at 13:56
fewlinesofcode
1,930515
1,930515
asked Nov 9 at 9:50
Fayyadh Kabir
1
asked Nov 9 at 9:50
Fayyadh Kabir
1
asked Nov 9 at 9:50
Fayyadh Kabir
1
1
keep in mind theint 21h, ah=1does return "characters" (or zero when extended scan code will be returned upon next call), not integers, so entering "-1" as user, when handled by this service, will need two calls, and values 45 (ASCII encoding for '-') and 49 (ASCII encoding for '1') will be returned. There are no DOS or BIOS services in PC to input integers, so you are on the correct path, but you must write your own code to handle multi-character input, and convert it from string into number (or you can use some library, not sure what emu8086 has in offer by default).
– Ped7g
Nov 9 at 13:05
(as now you are only printing negative/zero/positive, you don't even need to convert the string into integer, your current code is quite OK, it just needs some way to know how many chars it should read (if only single digit input values are allowed, then you need to read one or two chars, depending if "-" was used... also it would be nice then to support "+", i.e. "+4" as valid input))
– Ped7g
Nov 9 at 13:06
add a comment |
keep in mind theint 21h, ah=1does return "characters" (or zero when extended scan code will be returned upon next call), not integers, so entering "-1" as user, when handled by this service, will need two calls, and values 45 (ASCII encoding for '-') and 49 (ASCII encoding for '1') will be returned. There are no DOS or BIOS services in PC to input integers, so you are on the correct path, but you must write your own code to handle multi-character input, and convert it from string into number (or you can use some library, not sure what emu8086 has in offer by default).
– Ped7g
Nov 9 at 13:05
(as now you are only printing negative/zero/positive, you don't even need to convert the string into integer, your current code is quite OK, it just needs some way to know how many chars it should read (if only single digit input values are allowed, then you need to read one or two chars, depending if "-" was used... also it would be nice then to support "+", i.e. "+4" as valid input))
– Ped7g
Nov 9 at 13:06
keep in mind the
int 21h, ah=1 does return "characters" (or zero when extended scan code will be returned upon next call), not integers, so entering "-1" as user, when handled by this service, will need two calls, and values 45 (ASCII encoding for '-') and 49 (ASCII encoding for '1') will be returned. There are no DOS or BIOS services in PC to input integers, so you are on the correct path, but you must write your own code to handle multi-character input, and convert it from string into number (or you can use some library, not sure what emu8086 has in offer by default).– Ped7g
Nov 9 at 13:05
keep in mind the
int 21h, ah=1 does return "characters" (or zero when extended scan code will be returned upon next call), not integers, so entering "-1" as user, when handled by this service, will need two calls, and values 45 (ASCII encoding for '-') and 49 (ASCII encoding for '1') will be returned. There are no DOS or BIOS services in PC to input integers, so you are on the correct path, but you must write your own code to handle multi-character input, and convert it from string into number (or you can use some library, not sure what emu8086 has in offer by default).– Ped7g
Nov 9 at 13:05
(as now you are only printing negative/zero/positive, you don't even need to convert the string into integer, your current code is quite OK, it just needs some way to know how many chars it should read (if only single digit input values are allowed, then you need to read one or two chars, depending if "-" was used... also it would be nice then to support "+", i.e. "+4" as valid input))
– Ped7g
Nov 9 at 13:06
(as now you are only printing negative/zero/positive, you don't even need to convert the string into integer, your current code is quite OK, it just needs some way to know how many chars it should read (if only single digit input values are allowed, then you need to read one or two chars, depending if "-" was used... also it would be nice then to support "+", i.e. "+4" as valid input))
– Ped7g
Nov 9 at 13:06
add a comment |
1 Answer
1
active
oldest
votes
up vote
0
down vote
If your input is a digit string optionally prefixed with a -, you should check for a the optional - instead of checking if the ASCII code is > or < than 30h. If you only support single-digit numbers, then seeing a - means you need to read exactly 1 more byte.
answered Nov 9 at 10:08
Peter Cordes
117k16178305
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
0
down vote
If your input is a digit string optionally prefixed with a -, you should check for a the optional - instead of checking if the ASCII code is > or < than 30h. If you only support single-digit numbers, then seeing a - means you need to read exactly 1 more byte.
answered Nov 9 at 10:08
Peter Cordes
117k16178305
add a comment |
up vote
0
down vote
If your input is a digit string optionally prefixed with a -, you should check for a the optional - instead of checking if the ASCII code is > or < than 30h. If you only support single-digit numbers, then seeing a - means you need to read exactly 1 more byte.
answered Nov 9 at 10:08
Peter Cordes
117k16178305
add a comment |
up vote
0
down vote
up vote
0
down vote
If your input is a digit string optionally prefixed with a -, you should check for a the optional - instead of checking if the ASCII code is > or < than 30h. If you only support single-digit numbers, then seeing a - means you need to read exactly 1 more byte.
answered Nov 9 at 10:08
Peter Cordes
117k16178305
If your input is a digit string optionally prefixed with a -, you should check for a the optional - instead of checking if the ASCII code is > or < than 30h. If you only support single-digit numbers, then seeing a - means you need to read exactly 1 more byte.
answered Nov 9 at 10:08
Peter Cordes
117k16178305
answered Nov 9 at 10:08
Peter Cordes
117k16178305
answered Nov 9 at 10:08
Peter Cordes
117k16178305
answered Nov 9 at 10:08
Peter Cordes
117k16178305
117k16178305
add a comment |
add a comment |
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keep in mind the
int 21h, ah=1does return "characters" (or zero when extended scan code will be returned upon next call), not integers, so entering "-1" as user, when handled by this service, will need two calls, and values 45 (ASCII encoding for '-') and 49 (ASCII encoding for '1') will be returned. There are no DOS or BIOS services in PC to input integers, so you are on the correct path, but you must write your own code to handle multi-character input, and convert it from string into number (or you can use some library, not sure what emu8086 has in offer by default).– Ped7g
Nov 9 at 13:05
(as now you are only printing negative/zero/positive, you don't even need to convert the string into integer, your current code is quite OK, it just needs some way to know how many chars it should read (if only single digit input values are allowed, then you need to read one or two chars, depending if "-" was used... also it would be nice then to support "+", i.e. "+4" as valid input))
– Ped7g
Nov 9 at 13:06