program to compare two strings without using string instructions using 8086 compatible assembly language

ass12.asm

;program to compare two strings without using string instructions
INCLUDE io.h

Cr EQU 0ah
Lf EQU 0dh


data SEGMENT
p_str1 DB Cr, Lf, 'Enter 1st string: ',0
p_str2 DB Cr, Lf, 'Enter 2nd string: ',0
p_not1 DB Cr, Lf, 'The strings are not same because of different lengths',0
p_not2 DB Cr, Lf, 'The strings are not same because of different characters',0
p_same DB Cr, Lf, 'The strings are the same',0
str1 DB 100 DUP (?)
str2 DB 100 DUP (?)
data ENDS



code SEGMENT
	ASSUME cs:code, ds:data
start:	mov ax, data
	mov ds, ax
		;input str1
	output p_str1
	inputs str1, 100
	mov bx, cx
		;input str2
	output p_str2
	inputs str2, 100
		;compare lengths
	cmp bx, cx
	jne l_not1;if different length jump
		;initialize
	lea si, str1
	lea di, str2
		;iterate to compare characters
nxt_chk:mov al, [si];copy the two bytes in ax
	mov ah, [di]
	cmp al, ah;compare the two bytes
	jne l_not2;if not (ah==al)
	inc si;increment the two bytes
	inc di
	dec cx;decrement the count(string length)
	jz l_same;if count=0 the strings are same
	jmp nxt_chk;else jump to ceck next byte

l_not1:	output p_not1
	jmp quit
l_not2: output p_not2
	jmp quit
l_same:	output p_same

quit:	mov al, 00h
	mov ah, 4ch
	int 21h
code ENDS
END start