.model small
.stack 100h
.data
greeting db 'WELCOME TO YOUR CALCULATOR', 0Dh, 0Ah, '$'
menu db '1 - ADDITION', 0Dh, 0Ah, '2 - SUBTRACTION', 0Dh, 0Ah, '3 - MULTIPLICATION', 0Dh, 0Ah, '4 - DIVISION', 0Dh, 0Ah, '$'
choicePrompt db 'Enter your choice: $'
prompt1 db 'Enter 1st Number: $'
prompt2 db 'Enter 2nd Number: $'
resultMsg db 'The result is: $'
buffer db 6, ?, 5 dup(0) ; Buffer to store input (max 5 digits)
userChoice db ?
num1 dw 0
num2 dw 0
result dw 0
.code
main proc
mov ax, @data
mov ds, ax
; Print the greeting and menu
lea dx, greeting
mov ah, 09h
int 21h
lea dx, menu
mov ah, 09h
int 21h
; Print choice prompt
lea dx, choicePrompt
mov ah, 09h
int 21h
; Read user's choice
mov ah, 01h
int 21h
sub al, '0'
mov userChoice, al
call getch
; Print newline
call printNewline
; Print prompt1 and read first number
lea dx, prompt1
mov ah, 09h
int 21h
call readNumber
mov num1, ax
call printNewline
; Print prompt2 and read second number
lea dx, prompt2
mov ah, 09h
int 21h
call readNumber
mov num2, ax
; Perform the chosen operation
mov ax, num1
mov bx, num2
cmp userChoice, 1
je additionOp
cmp userChoice, 2
je subtractionOp
cmp userChoice, 3
je multiplicationOp
cmp userChoice, 4
je divisionOp
jmp endProgram
additionOp:
add ax, bx
mov result, ax ; Store the result
jmp displayResult
subtractionOp:
sub ax, bx
mov result, ax ; Store the result
jmp displayResult
multiplicationOp:
mul bx
mov result, ax ; Store the result
jmp displayResult
divisionOp:
xor dx, dx
div bx
mov result, ax ; Store the result
jmp displayResult
displayResult:
; Print the result message
lea dx, resultMsg
mov ah, 09h
int 21h
; Print the actual result
mov ax, result
call printNumber
; Print a newline
call printNewline
ret
endProgram:
mov ah, 4Ch
int 21h
main endp
getch proc
mov ah, 07h
int 21h
ret
getch endp
readNumber proc
lea dx, buffer
mov ah, 0Ah
int 21h
lea si, buffer + 2
mov cx, 0
convertLoop:
lodsb
cmp al, 0Dh
je endConvert
sub al, '0'
mov bx, 10
mul cx
add cx, ax
jmp convertLoop
endConvert:
mov ax, cx
ret
readNumber endp
printNewline proc
mov ah, 02h
mov dl, 0Dh
int 21h
mov dl, 0Ah
int 21h
ret
printNewline endp
printNumber proc
mov bx, 10
xor cx, cx
convertLoop2:
xor dx, dx
div bx
add dl, '0'
push dx
inc cx
cmp ax, 0
jne convertLoop2
printLoop:
pop dx
mov ah, 02h
int 21h
loop printLoop
ret
printNumber endp
end main
So I'm trying to make a simple calculator where the user can choose what arithmetic operation will be used, will prompt the user to enter numbers maximum numbers of 5 twice and displays the result, but I'm having trouble with displaying the total result, after the 2nd number was inserted by the user, the "Enter 2nd Number: " will be removed and will be replaced by "The result is: 0: 21" assuming the number 21 was the inserted integer in prompt2, the code should be able to let the user choose one of the following arithmetic operator, lets the user to enter integers maximum of 5 numbers and adds or subtract it depending to what arithmetic operation the user chose and displays the result in the end
Between entering the 1st and the 2nd number you issue a call printNewline, but you forget to do the same between inputting the 2nd number and displaying the result. That's why the 2nd prompt got overwritten. An interesting solution would be to include the newline codes in the result message already: resultMsg db 13, 10, 'The result is: $'
If the user inputs a number that has 5 digits, you will lose the info about the operation to be performed on the numbers. The reason for this is that the buffer is 1 byte short. Correct setting: buffer db 6, ?, 6 dup(0) ; max 5 digits userChoice db ?
The convertLoop is wrong in its use of mul cx. That form of the mul instruction multiplies AX by CX and leaves the product in DX:AX.
Better keep the result that is under construction in AX and replace that lodsb (that mandatory uses AL) by other instructions that don't touch AX:
lea si, buffer + 2
xor ax, ax
convertLoop:
mov cl, [si]
inc si
cmp cl, 13
je endConvert
and cx, 15 ; ['0','9'] -> [0,9]
mov bx, 10
mul bx
add ax, cx
jmp convertLoop
endConvert:
ret