Operation on Strings in Assembly Language

Write a Program for Operation on Strings in Assembly Language. Using Macro display the Menu for entering string, calculate length, reverse, palindrome and exit. Accept the choice from user using INT 21H function 01H.

Choice = 1: Call procedure for accepting string. Using interrupt INT 21H, function 0AH accept the string and end procedure. Return back to display Menu.

Choice = 2: Call procedure for finding length of the string. Display length and return back to display Menu.

Choice = 3: Call procedure to reverse the string. Display the reverse string and return back to display Menu.

Choice = 4: Call procedure to check if entered string is palindrome. If palindrome displays, the string is a palindrome, otherwise display String is not a palindrome.

Choice = 5: Terminate the program. If any other key is pressed display invalid choice.

Algorithm for Operation on Strings

Step I : Initialize the data and stack memory.

Step II : Using Macro display Menu.

1. Accept

2. Length

3. Reverse

4. Palindrome

5. Exit.

Step III : Accept choice from user using INT 21H, function 01H.

Step IV : IS choice = 1 jump to step XI else goto step V.

Step V : IS choice = 2 jump to step XIV else goto step VI.

Step VI : IS choice = 3 jump to step XVII else goto step VII.

Step VII : IS choice = 4 jump to step XX else goto step VIII.

Step VIII : IS choice = 5 jump to step XXIII else goto step IX.

Step IX : Display Wrong choice.

Step X : Jump to step II.

Step XI : Call procedure accept.

Step XII : Accept string using INT 21H, function 0AH.

Step XIII : Return to main program and goto step II.

Step XIV : Call procedure length.

Step XV : Calculate the length of string and display it using INT 21H, function 02H.

Step XVI : Return back to main program and jump to step II.

Step XVII : Call procedure reverse.

Step XVIII : Reverse the string and display it.

Step XIX : Return back to main program and jump to step II.

Step XX : Call procedure palindrome.

Step XXI : Check if string is palindrome. If yes display string is palindrome else string is not a palindrome.

Step XXII : Return back to main program and jump to step II.

Step XXIII : Terminate the program and stop.

Operation on Strings Assembly Language code

 TITLE  STRING OPERATIONS  <br/> MESS  MACRO MSG     ; DEFINITION OF MACRO MESS         <br/>      MOV      AH, 09H  <br/>      LEA      DX, MSG  <br/>      INT      21H  <br/>      ENDM  <br/> .MODEL SMALL   <br/> .STACK 100H  <br/> .DATA  <br/>      STR1      DB 25 , ? , 25 DUP('$')   <br/>      STR3      DB 25 , ? , 25 DUP('$')   <br/>      MSG1      DB 0AH, 0DH, 'MENU $'  <br/>      MSG21      DB 0AH, 0DH, '1.ACCEPT $'  <br/>      MSG22      DB 0AH, 0DH, '2.LENGTH $'  <br/>      MSG23      DB 0AH, 0DH, '3.REVERSE $'  <br/>      MSG24      DB 0AH, 0DH, '4.PALINDROME $'  <br/>      MSG25      DB 0AH, 0DH, '5.EXIT $'  <br/>      MSG3      DB 0AH, 0DH, 'ENTER YOUR CHOICE : $'  <br/>      MSG4      DB 0AH, 0DH, 'WRONG CHOICE $'  <br/>      MSG5      DB 0AH, 0DH, 'ENTER THE STRING : $'  <br/>      MSG6      DB 0AH, 0DH, 'STRING IS : $'  <br/>      MSG7      DB 0AH, 0DH, 'LENGTH IS : $'  <br/>      MSG8      DB 0AH, 0DH, 'THE STRING IS A PALINDROME  $'  <br/>      MSG9      DB 0AH, 0DH, 'THE STRING IS NOT A PALINDROME  $'  <br/> .CODE   <br/> mov     ax,           @data     ; Intialize data and extra segment  <br/>      mov           ds, ax  <br/>      mov           es, ax  <br/> ak :     mess           msg1     ; display menu  <br/>      mess           msg21  <br/>      mess           msg22  <br/>      mess           msg23  <br/>      mess           msg24  <br/>      mess           msg25  <br/>      mess           msg3     ; accept choice  <br/>      mov           ah, 01h  <br/>      int           21h  <br/>      mov           bl, al     ; Choice BL  <br/>      cmp          bl, 31h     ; if choice=1  <br/>      je           acc          ; Accept string  <br/>      cmp           bl, 32h     ; if choice=2  <br/>      je           len          ; Find lenth   <br/>                                    ; of string  <br/>      cmp           bl, 33h     ; if choice=3  <br/>      je           rev          ; Reverse string  <br/>      cmp           bl, 34h     ; if choice=4  <br/>      je           pal          ; Check if string is   <br/>                                    ; palindrome  <br/>      cmp           bl, 35h     ; if choice=5  <br/>      je           endd     ; exit  <br/>      mess           msg4     ; Wrong Choice  <br/>      jmp           ak  <br/> acc :     call           accept  <br/>      jmp           ak  <br/> len :     call           lent  <br/>      jmp           ak  <br/> rev :     call           reverse  <br/>      jmp           ak  <br/> pal:     call           pall  <br/>      jmp           ak  <br/> endd:     mov           ah, 4ch  <br/>      int           21h  <br/> ;      accept      procedure                                            <br/>      accept proc near  <br/>      mess      msg5  <br/>      mov      ah, 0ah     ; Accept String  <br/>      lea           dx, str1  <br/>      int           21h  <br/>      RET  <br/> accept endp  <br/> ; length procedure    <br/> lent proc near     <br/>      mess           msg7   <br/>      mov           dl, str1+1     ; Dl contains length of String  <br/>      or           dl, 30h  <br/>      mov
     ah, 02h          ; Display Length                           <br/>      int           21h  <br/>      ret   <br/> lent endp  <br/> ; reverse procedure    <br/> reverse proc near  <br/>      mess           msg6  <br/>      mov           ch, 00h  <br/>      mov           cl, str1+1     ; Cl has length of string  <br/>      sub           cl, 01h  <br/>      lea           si, str1+2     ; DESTINATION STRING  <br/>      lea           di, str1+2     ; DESTINATION STRING  <br/>      repz           movsb          ; COPY TO TRAVERSE TILL END OF FIRST STR  <br/>      mov           cl, str1+1         <br/>      lea           di, str3+2     ; DESTINATION STRING  <br/> loop1:      mov           dx, [si]          ; dx contains rightmost character  <br/>      mov           ah, 02h  <br/>      int           21h          ; display character  <br/>      mov           [di], dx          ; copy character to destination  <br/>      dec           si  <br/>      inc           di  <br/>      dec           cl  <br/>      cmp           cl, 00h  <br/>      jne           loop1  <br/>      ret  <br/> reverse endp  <br/> ; palindrome procedure    <br/> pall      proc           near  <br/>      mess           msg6  <br/>      mov           ah, 09h  <br/>      lea           dx, str1+2     ; str1 contains original string  <br/>      int           21h  <br/>      call           reverse               ; str3 has reversed string   <br/>      lea           di, str3+2  <br/>      mov           ah, 00h  <br/>      mov           dh, 00h  <br/>      lea           si , str1+2  <br/>      mov           cl, str1+1          ; CL contains Length of string  <br/> loop 2 :     mov           al, byte ptr[si]  <br/>      mov           bl, byte ptr[di]  <br/>      dec           cl                    ; Decrement count  <br/>      cmp           cl, 00h  <br/>      je           loopa  <br/>      cmp           al, bl               ; Compare characters  <br/>      je           loop3               ; if same goto loop3  <br/> loopa : cmp           cl, 00h               ; if checked all characters  <br/>      je           loop4  <br/>      mess           msg9               ; the strings are not same  <br/>      jmp           loop5  <br/> loop4 : mess           msg8               ; the strings are same  <br/> loop5: ret  <br/> loop3 : inc           si  <br/>      inc           di  <br/>      jmp           loop2               ; now check next character  <br/>      pall           endp  <br/> end

TITLE STRING OPERATIONS MESS MACRO MSG ; DEFINITION OF MACRO MESS MOV AH, 09H LEA DX, MSG INT 21H ENDM .MODEL SMALL .STACK 100H .DATA STR1 DB 25 , ? , 25 DUP('$') STR3 DB 25 , ? , 25 DUP('$') MSG1 DB 0AH, 0DH, 'MENU $' MSG21 DB 0AH, 0DH, '1.ACCEPT $' MSG22 DB 0AH, 0DH, '2.LENGTH $' MSG23 DB 0AH, 0DH, '3.REVERSE $' MSG24 DB 0AH, 0DH, '4.PALINDROME $' MSG25 DB 0AH, 0DH, '5.EXIT $' MSG3 DB 0AH, 0DH, 'ENTER YOUR CHOICE : $' MSG4 DB 0AH, 0DH, 'WRONG CHOICE $' MSG5 DB 0AH, 0DH, 'ENTER THE STRING : $' MSG6 DB 0AH, 0DH, 'STRING IS : $' MSG7 DB 0AH, 0DH, 'LENGTH IS : $' MSG8 DB 0AH, 0DH, 'THE STRING IS A PALINDROME $' MSG9 DB 0AH, 0DH, 'THE STRING IS NOT A PALINDROME $' .CODE mov ax, @data ; Intialize data and extra segment mov ds, ax mov es, ax ak : mess msg1 ; display menu mess msg21 mess msg22 mess msg23 mess msg24 mess msg25 mess msg3 ; accept choice mov ah, 01h int 21h mov bl, al ; Choice BL cmp bl, 31h ; if choice=1 je acc ; Accept string cmp bl, 32h ; if choice=2 je len ; Find lenth ; of string cmp bl, 33h ; if choice=3 je rev ; Reverse string cmp bl, 34h ; if choice=4 je pal ; Check if string is ; palindrome cmp bl, 35h ; if choice=5 je endd ; exit mess msg4 ; Wrong Choice jmp ak acc : call accept jmp ak len : call lent jmp ak rev : call reverse jmp ak pal: call pall jmp ak endd: mov ah, 4ch int 21h ; accept procedure accept proc near mess msg5 mov ah, 0ah ; Accept String lea dx, str1 int 21h RET accept endp ; length procedure lent proc near mess msg7 mov dl, str1+1 ; Dl contains length of String or dl, 30h mov

ah, 02h ; Display Length int 21h ret lent endp ; reverse procedure reverse proc near mess msg6 mov ch, 00h mov cl, str1+1 ; Cl has length of string sub cl, 01h lea si, str1+2 ; DESTINATION STRING lea di, str1+2 ; DESTINATION STRING repz movsb ; COPY TO TRAVERSE TILL END OF FIRST STR mov cl, str1+1 lea di, str3+2 ; DESTINATION STRING loop1: mov dx, [si] ; dx contains rightmost character mov ah, 02h int 21h ; display character mov [di], dx ; copy character to destination dec si inc di dec cl cmp cl, 00h jne loop1 ret reverse endp ; palindrome procedure pall proc near mess msg6 mov ah, 09h lea dx, str1+2 ; str1 contains original string int 21h call reverse ; str3 has reversed string lea di, str3+2 mov ah, 00h mov dh, 00h lea si , str1+2 mov cl, str1+1 ; CL contains Length of string loop 2 : mov al, byte ptr[si] mov bl, byte ptr[di] dec cl ; Decrement count cmp cl, 00h je loopa cmp al, bl ; Compare characters je loop3 ; if same goto loop3 loopa : cmp cl, 00h ; if checked all characters je loop4 mess msg9 ; the strings are not same jmp loop5 loop4 : mess msg8 ; the strings are same loop5: ret loop3 : inc si inc di jmp loop2 ; now check next character pall endp end

How to Run this Program

For Running this program you should have installed Tasm on you computer . If you have not installed Tasm yet please install from Here .

C:\programs>tasm str

Assembling file: str.ASM

Error messages: None

Warning messages: None

Passes: 1

Remaining memory: 434k

C:\programs>tlink str

C:\programs>str

1. ACCEPT

2. LENGTH

3. REVERSE

4. PALINDROME

5. EXIT

ENTER YOUR CHOICE : 1

ENTER THE STRING : college

1. ACCEPT

2. LENGTH

3. REVERSE

4. PALINDROME

5. EXIT

ENTER YOUR CHOICE : 2

LENGTH IS : 7

1. ACCEPT

2. LENGTH

3. REVERSE

4. PALINDROME

5. EXIT

ENTER YOUR CHOICE : 3

STRING IS : egelloc

1. ACCEPT

2. LENGTH

3. REVERSE

4. PALINDROME

5. EXIT

ENTER YOUR CHOICE : 4

STRING IS : college

STRING IS : egelloc

THE STRING IS NOT A PALINDROME

1. ACCEPT

2. LENGTH

3. REVERSE

4. PALINDROME

5. EXIT

ENTER YOUR CHOICE : 1

ENTER THE STRING : madam

1. ACCEPT

2. LENGTH

3. REVERSE

4. PALINDROME

5. EXIT

ENTER YOUR CHOICE : 4

STRING IS : madam

THE STRING IS A PALINDROME

Source projectgeek.com

Operation on Strings in Assembly Language

Algorithm for Operation on Strings

How to Run this Program

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