very basic assembly question

[kryptonite0110]

I've been reading a lot of assembly tutorials(though it wont probably sound like it), but the only question i have is how do you write to variables? I understand registers, and creating variables, but how can you change a variable's value?????

[lazy13]

When you want to change a viriables value:
a)if you have a variable on a register you just change the registers value
b)if your variable is in memory then you store your value in the position of memory that your variable is.

[rcgreen]

I don't know all the ways to do it, but the simplest
is the db (define byte) statement:

org 100h

section .data

string                                      ;put any string here
db "hello, world!"
string_length equ $ -string                 ;calculates the length

section .text

BEGIN:

mov bx,0001h                                ;write to stdout
mov ah,40h                                  ;write to file or device
mov dx,string                               ;address of buffer 
mov cx,string_length                        ;length
int 21h                                     ;dos call
mov ah,4ch                                  ;terminate
int 21h                                     ;dos call

see also

[kryptonite0110]

How do you find the position of a variable?

[rcgreen]

You refer to it by name. mov dx,string puts its address into
the dx register.

[kryptonite0110]

so if i say:
integer equ 1
mov dx, integer
mov dx, 7

integer will then equal 7? If this is true, how do i remove the integer from the dx register?