Hey guys, how can I add two numbers stored in asciiz format ?
str1 db "2",0
str2 db "3",0

You mean to end up with the equivalent of
str3 db "23",0

Do you first know how to copy a string (in C, this is strcpy)
strcat is basically just strcpy called twice, the second starting at the end of the first copy.

Actually no. I mean add 2+3=5
The Answer Must Be "5"

So which bit are you stuck on?
- string to int conversion
- addition
- int to string conversion

And what have you tried?

thx a lot for your reply. I've already solved the problem by (ustr2dw and ustr2dw)