[Assembley Code]How to convert upper case to lower case and vice versa

; Name: Arpan Chavda

; Roll No.:09BCE006

; Aim: Enter string from user and convert upper case to lower case and

; vice versa without change in entered number in string.

;it runs on tasm assembler



read macro str1

    mov ah,0ah

    lea dx,str1

    int 21H

endm



disp macro str

     mov ah,09h

     lea dx,str

     int 21h

endm



data segment

str1 db 20

     db 0

     db 20 dup('$')

msg1 db "Enter the String : $"

msg2 db "Coverted string is:$"

nl db 0dH,0AH,'$'

data ends

code segment

assume cs:code,ds:data

start:

 mov ax,data

 mov ds,ax

 disp msg1

 read str1

 lea si,str1

 inc si

 mov cx,[si]

 dec cx



 lp1:  inc si

         mov al,[si]

  cmp al,39H

  jc skip

  mov al,[si]

  cmp al,5aH

  jnc subt

  mov al,[si]

  add al,20H

  mov [si],al

  jmp skip



 subt:   mov al,[si]

  sub al,20H

  mov [si],al



 skip: loop lp1



        disp nl

 disp msg2

 disp nl

 disp str1+2

 mov ah,4ch

 int 21h

code ends

end start





Output:





D:\BORLANDC\BIN>tasm str.asm

Turbo Assembler  Version 3.1  Copyright (c) 1988, 1992 Borland International



Assembling file:   string.asm

Error messages:    None

Warning messages:  None

Passes:            1

Remaining memory:  459k



D:\BORLANDC\BIN>tlink str.obj

Turbo Link  Version 5.1 Copyright (c) 1992 Borland International

Warning: No stack



D:\BORLANDC\BIN>str.exe

Enter the String : as99DDF

Converted string is:

AS99ddf