7. Program to Copy a String in Reverse Order in Assembly Language using Visual Studio

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Chapter 3

Assembly Language Fundamentals

Assembly Language Programming Exercise

Problem # 7:

Write a program with a loop and indirect addressing that copies a string from source to target, reversing the character order in the process. Use the following variables:
source BYTE "This is the source string",0
target BYTE SIZEOF source DUP('#')

Solution:

.386
.model flat,stdcall
.stack 4096
ExitProcess PROTO, dwExitCode:DWORD

    .data
    source BYTE "This is the source string",0
    target BYTE SIZEOF source DUP('#')

    .code
    main PROC
        mov esi,0
        mov edi,LENGTHOF source - 1
        mov ecx,SIZEOF source

    L1:
        mov eax, 0
        mov al,source[esi]
        mov target[edi],al
        inc esi
        dec edi
        loop L1

INVOKE ExitProcess,0
main ENDP
END main

Let me know in the comment section if you have any question.

Previous Post:
Program to Reverse an Array in Assembly Language using Visual Studio

Comments

  1. Unknown9 October 2018 at 16:20

    hi, thank you for this tutorial.

    I'd like to know how to display source and target strings.

    ReplyDelete
    Replies
    1. Hadiqa Aman Ullah19 November 2018 at 00:03

      You can use WriteString function from Irvine32 library as follows:
      mov edx,OFFSET source
      call WriteString
      mov edx,OFFSET target
      call WriteString

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      Delete
  2. Unknown10 February 2020 at 15:11

    The second line of code within the loop should be "mov al, source[edi]" not "mov al, source[esi]".

    ReplyDelete
  3. Unknown1 March 2020 at 23:20

    its -2 not -1

    ReplyDelete

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