How to compare two strings assembly

Question

Could anyone tell me how to compare two strings in assembly language, I`ve written the followign, but it does not seem to work.

assume cs:code, ds:data

data seg         


        

Answer 1

I had the same problem when I was writing asm in school, years ago. The problem I encountered was that I wanted to compare the word "exit" with a user entry. If they typed "exit", the application quit. If they typed anything else, then a message appeared telling them there was an erroneous entry.

The way I solved the issue was to compare the strings character-by-character, until the characters no longer matched, or vice-versa.

This also might be of some use. Here are some code examples relating to string comparison in assembly language: http://www.daniweb.com/software-development/assembly/threads/58667/assembly-language-comparing-strings

You might also want to look at this article relating to regular expressions (regex) in assembly language: Regular Expressions and Assembly

Answer 2

j is jump l is less e is equel if bl=a & bh=k here cmp is work like a-k

if here 0 or less-equal value then jle work. then n will work. if positive value jle is not work.

cmp bl,bh jle n

mov ah,2 mov dl,bh int 21h

n: mov ah,2 mov dl,bl int 21h