How to compare two strings in assembly language. The program is written in 16-bit x86 MASM Assembly.

How to compare two strings in assembly language data greet: db "Type a word: " greetL: e Welcome to `r/asm`, the subreddit for Assembly language in all Instruction Set Architectures! We would like to show you a description here but the site won’t allow us. bss input: resq 100 section . Here we will see some instructions which are used to manipulate the string related operations. Else, regardless of the outcome of the comparison, will the code at same get executed. You need to load one of them in a register before comparing with the other: mov al, string[si] cmp al, wrd[di] je same same: You need something in between here (whatever you want in case of 'not equal'). Mar 24, 2017 · And the second thing is finding out how I can compare the two strings. How does Compare work in assembly language? The CMP instruction compares two operands. Problem: Write an assembly language program that prompts a user to enter two integers and, if the first number is smaller than the second number, it prints "First number is lesss than second". cmp is typically executed in conjunction with conditional jumps and the setcc instruction. Use subroutine. How to compare two files? String operations like compare strings, concatenate strings, find length, reverse string, Find string and word in a file using while loop Jun 17, 2024 · Learn how to compare two strings in 8086 assembly language with this simple program. The specific instructions and techniques used depend on the assembly language and architecture. The CPU compares the string referenced by es:di to the string pointed at by ds:si. Oct 9, 2024 · The point of this post is to focus on the string comparison function and show off two really convenient instructions. Jul 15, 2024 · Welcome to AlgoBangla29,🔴 What You'll Learn:Introduction to Assembly Language ProgrammingStep-by-step guide on how to compare two strings in Assembly Langua I want to compare two strings in x86 assembly. The program is written in Assembly 8086. The program is written in 16-bit x86 MASM Assembly. hi, im really new to this programming language and im having a hard time in strings. can anyone teach me how to compare strings the easiest way. Perfect for beginners and intermediate C programmers. The task should demonstrate: Comparing two strings for exact equality Comparing two strings for inequality (i. If an operand greater than one byte is compared to an immediate byte, the immediate byte value is first sign-extended. e. (20 points) Write an assembly language program to compare two strings of the same length. Mar 21, 2025 · A detailed guide on how to effectively compare two characters in a string using assembly language with the emu8086 emulator. ) In this video, you will be learning how to compare two strings in MASM32If you like my content, please consider liking this video and subscribing for more vi Dec 17, 2022 · Can someone please help me. String is either referred as byte string or word string.  The program should:h) Use Real Mode Programmingi) Use Indirect Addressing Modej) Use Irvine16 library for Outputk) Two strings must be assigned within the definition of the stringsl) Use EQU and $ operators to calculate the size of the stringm) Display the Jan 27, 2017 · The following is my code in assembly language to compare two numbers and print a test character to confirm if it's written correctly. Assembly language course - Compare Two String -||- كورس لغة التجميع Blast Academy 168 subscribers 9 Learn how to correctly compare strings in assembly language. Beware of overflows!. The 80x86's string instructions are also useful for manipulating arrays, tables, and records. It is used in multiplication and division. This guide explains how it works, includes real examples, and shows common mistakes to avoid. What you want instead is JE, which means jump only if the values are exactly the same. I read some examples and I write this : GETSTR MACRO STR MOV AH,0AH LEA DX,STR INT 21H ENDM PRINTSTR MACRO STR MOV AH, Title:- Assembly Language Program for comparing two strings (8086)Hello, Guy's In this video I will Show you how to write a program for comparing two string Description Compares the byte, word, or long in DS: [ (E)SI] with the byte, word, or long in ES: [ (E)DI}. Part of this is to compare the length of 2 strings (I have their adresses in 2 registers) and return 0 if they are the same length, +1 if the first is longer and -1 if the first is shorter. Different String Manipulation Instructions The string is a series of data bytes or words available in memory at consecutive locations. Then I thought other people may find it … Jun 23, 2022 · Time Complexity: O (min (n,m)) where n and m are the length of the strings. This instruction basically subtracts one operand from the other for comparing whether the operands are equal or not. 7K subscribers Subscribed The 8088, 8086, 80186, and 80286 can process two types of strings: byte strings and word strings. Requirements: Write a program, compare whether the characters contained in both strings String1 and String2 are the same; if the same is displayed, 'match' is displayed, otherwise the 'NO Match' is displayed. Operations include storing strings in memory, loading strings from memory, comparing strings, and scanning strings for substrings. program to compare two strings using string instructions using 8086 asm lang. Description Subtracts operand1 from operand2, but does not store the result; only changes the flags. In this tutorial, you will learn to compare two strings using the strcmp () function. Differences between C++ Relational operators and compare () :- compare () returns an int, while relational operators return boolean value i. 4 For comparing strings in x86-assembly there is a special OpCode named CMPS (Compare Strings). I want to compare two string using "cmps". I'm trying to take a 32bit input number and compare it to a list of 32 bit numbers (which are bit patterns, eg '0101010', '11001100', etc) and find the pattern that has the most bits in common with the input. May 10, 2019 · assembly to compare 2 input number . The explicit-operands form (specified with the CMPS mnemonic) allows the two source operands to be specified explicitly. This is a subreddit for people who need help with programming in assembly and people who want to post their own code to help others out. Jul 22, 2018 · A Summary of x86 String Instructions I have never managed to memorize all of x86 Assembly’s string instructions — so I wrote a cheat sheet for myself. Nov 12, 2023 · Manipulating strings in assembly language involves a series of operations to perform tasks such as copying, comparing, concatenating, or searching for substrings within a string. I understand how jumps and comparisons work and can make loops just fine just dont know how to go about comparing the strings Here is the example: Input: String1 : gtaghgrjgnbkjhugtajghygta String2 : gta Output: There are 3 "gta" string in String1, in index 0, 15, 22. If the two strings have the same length and match in all their characters, they are equal. You can easily assign or Jul 11, 2025 · Key String manipulation instruction in 8086 instruction sets includes different instructions such as MOVSB, CMPSB, SCASB, LODSB, STOSB, and other instructions which are going to be discussed further. The compare strings and the Move strings. One of them is read from a file and the other one is read from keyboard and both are saved in a variable. Auxiliary Space: O (max (n,m)) where n and m are the length of the strings. The assembler merely converts each instruction source line into binary. Improve your coding skills today! 🆚 Comparing Two Strings Using 8086 Assembly Language | Microprocessor Lab Experiment 🆚 In this video, we demonstrate how to compare two strings character by character using 8086 Assembly Assembly language programming, to compare two strings are the same Write a program, comparing two-byte string 5 and OLDS NEWS, if the same, set the RESULT 0, otherwise, it is 0FFH. This guide is beginner-friendly, so don’t worry if you’re new to assembly programming. I'm trying to get my program to read in 2 characters, compare them, and then output the smaller character. ---This video is based The CMPS instruction can be used to compare a byte in one string with a byte in another string or to compare a word in one string with a word in another string. I'm moving 3 into both variables. It is generally used in conditional execution. As for your next question, it sounds like a counter error, or finding the string termination to early. We have already used variable length strings in our previous examples. Code for Program to compare two strings. After entering two strings, the parameters such as the register must be made must be set, and then the string operation The 8088, 8086, 80186, and 80286 can process two types of strings: byte strings and word strings. Hi all, I'm having a problem with comparing two strings and telling the user if they are equal or not. It also has two variants: cmpsb and cmpsw. Both strings are ended with byte with value 0, and location of strings are registers ESI and EDI. This explicit-operand form is String operations like compare strings, concatenate strings, find length, reverse string, Find string and word in a file using while loop Program to compare two characters and display message accordingly Assembly language programmers can also use character data to implement more complex functions, such as string manipulation functions and text editors. Apr 10, 2014 · JAE means jump if above or equal, that is to say when you compare to 'A', the jump will be taken for any character with an encoding greater or equal to 'A'. 8086 Programming -Compare two Strings JANAPATI SIVAVARA PRASAD 1. this video also implement loop and label etc. Lawlor In both C or assembly, you can allocate and access memory in several different sizes: C/C++ datatype The string instructions operate on strings of bytes. The length of the strings is given to you in another location called LENGTH Your program will compare both the strings finally display to the user whether they are identical or not. Feb 3, 2020 · 0 Basically I am trying to compare two strings in assembly, see code below: global _start section . The length of the equality check (preferrably the longest string) is set in ECX. This instruction compares two data items of one byte, word or doubleword, pointed to by the DS:SI and ES:DI registers and sets the flags accordingly. Jun 12, 2025 · In this focused session, we dive deep into the CMPS (Compare String) instruction — a core part of string operations in 8086 Assembly Language. They can move strings, compare strings, search for a specific value within a string, initialize a string to a fixed value, and do other primitive operations on strings. May 7, 2025 · Comparing two strings in assembly language 8086 involves meticulously examining each character of both strings to determine if they are identical. Compare two strings 1. Like the movs instruction, the MASM assembler allows several different forms of this instruction: {REPE} CMPSB {REPE} CMPSW {REPE} CMPSD ;Available only on 80386+ {REPE} CMPS dest, source {REPNE CMPS The instruction cmps is used to compare two strings. 76K subscribers Subscribed This assembly language program allows users to perform various string manipulation operations, including string copy, string compare, and string search. Additionally, if you have any questions, you can comment Apr 28, 2015 · I need to compare a string which is saved in Code memory location of the 8051 starting from 200H with another three strings which are also saved in the Code memory location this time staring from 3 Apr 11, 2014 · I have the two words stored in variables just called first and second. Here is an example of a simple assembly language function that copies a string from one memory location to another. For this purpose, you will write assembly versions of (a) the strcmp() function and (b) the atoi() function. Below is a general overview of common string manipulation operations: 1. I'm new in assembly. Let's look at the example below: : lds si, [src] les di, [dest] cld mov cx, 100 rep cmpsb jne @@mismatch @@match Compare 2 strings in arm assembly Hey guys, I am a beginning comp science student and have to do a task in arm assembly. Nov 20, 2024 · In this blog, we’ll recreate two popular C standard library functions, strlen and strcmp, in assembly language and learn how to call them from a C program. 8086 ASSEMBLY LANGUAGE PROGRAMS(FOR THEORY ONLY) In Assembly Language Program(ALP) , we use three accumulators, one is AL for 8-bit operation, AX for 16-bit operation. CS 301: Assembly Language Programming Lecture, Dr. , the inverse of exact equality) Comparing two strings to see if one is lexically ordered before than the other Comparing two strings to see if one is lexically ordered after This video explore the concept of Comparing two arrays in Assembly 8086 Programming Language. At the assembly-code level, two forms of this instruction are allowed: the “explicit-operands” form and the “no-operands” form. Generally, we specify the length of the string by either of the two ways ? My task is to write a short assembly program where: There are two strings consist of only small letters of latin alphabet, coded in ASCII as two byte strings placed in memory. It does not disturb the destination or source operands. what Nov 28, 2010 · Assembly Language character and string operations summary This web page examines string and character instructions in assembly language. 06K subscribers Subscribed How to compare two values in assembly language? As a general rule, I think you’ll find that assembly language involves writing a large number of simple instructions to do anything. A processor understands only machine language instructions, which are strings of 1's and 0's. GitHub Gist: instantly share code, notes, and snippets. Apr 12, 2014 · I've looked at How to compare two strings assembly and I'm am trying to compare character by character until a character doesn't match and I can't seem to get my code to function how I want it to. You can also use the conditional jump instructions along with this instruction. I did most of the work but I want to compare the the user input and the string I provide in the code but Feb 22, 2012 · I know its the same question, both code compare, and both code had problems. How do I compare the characters of each string to see which one is larger? section . There is multiple ways we could return some value to let us know if the string comparison was successful, but I typically like to just return 0 if success and -1 on failure. Fix common mistakes and get accurate output with this step-by-step guide. Wide arrays or UTFs or others may vary, but standard C strings are 8-bits, hence your compare works. Apr 5, 2017 · If you are looking for a Assembly program to input two numbers and check if they are equal, unequal, greater or lesser or a assembly program to find the largest number between two numbers or how to check the numbers are equal or unequal You are at right place. The variable length strings can have as many characters as required. I've done stuff like this in Java for school assignments; finding the Hamming distance between two These set of instructions are called 'machine language instructions'. Jul 13, 2021 · It sounds like you are assuming a string memory layout similar to Pascal (with a max string length of 255). Compare both strings and set the flags CF and ZF in the given manner: We would like to show you a description here but the site won’t allow us. Cx contains the length of the two strings (when using the rep prefix). Feb 2, 2015 · 1 So I'm learning Assembly for the LC-3 Machine for the first time, so I'm still quite a newbie at this. data hello: db "Enter Message> ", 15 pass: db "password", 8 section . Welcome to this Assembly Language Programming Tutorial in MASM. The 80386 and later processors also handle double word strings. text mov eax, 4 mov ecx, hello mov edx, 15 int 0x80 mov eax, 3 mov ecx, input mov edx, 100 int 0x80 mov esi, input mov edi, pass cmp esi, edi jne The 80x86 CPUs can process three types of strings: byte strings , word strings, and double word strings. Before executing the cmps instruction, load the index values into the SI source- and DI destination-index registers. Assembly language is a low-level programming language that is specific to a particular computer architecture. This tutorial will wrap up the final two string instructions. Write a program to compare two strings. The 8088 microprocessor provides us a set of instructions called block processing or string instructions that allow us to achieve just that. Dec 31, 2012 · Could anyone tell me how to compare two strings in assembly language, I`ve written the followign, but it does not seem to work. Specific examples of instructions from various processors are used to illustrate the general nature of assembly language. You do use it by setting ESI to the source string and EDI to the destination string. Usually, we tend to use more of cmpsb. Didn't find what you were looking for? Find more on Program to compare two strings Or get search suggestion and latest updates. You can move from the source to The objective of this first assignment is to write two fairly short programs in MIPS assembly language and execute them using SPIM to verify that they work. So far what I've done is store the first character in register 1, and the second in register 2. The five string instructions are: STOS: Store string LODS: Load string CMPS: Compare string SCAS: Scan string MOVS Title:- Concat two strings using assembly language (8086), #microprocessor, #8086 Hello, Guy's In this video I will Show you how to write a program for conca Dec 11, 2022 · cmp string[si], wrd[di] You can't compare two memory bytes like that. I'm new to assembly, and I have to do the following: Write an assembly language program that allows you to enter two lines of no more than 50 characters from the keyboa To process strings in Assembly, we need to be able to process blocks of data in one go. hey all, im trying to compare two strings 8 characters long, the first was predefined and the second was entered by the user. It takes two strings (array of characters) as arguments, compares these two strings lexicographically, and then returns some value as a result. DX is for 32 bit operations if the result or output exceed 16-bits. But in assembly, there is no "string" datatype. Question: Write an Assembly Language program to compare two strings and display if they are equal. assume cs:code, ds:data data segment sirlung db "abcdjjj" lungimelu The CMPS instruction compares two strings. Title: Comparison strings are equal 2. Following is the complete program with comments as you can understand easily. Use subroutine in Assembly Language DIS MACRO STR MOV AH,09H LEA DX,STR INT 21H ENDM DATA SEGMENT MSG1 DB "ENTER THE STRING : $" MSG2 DB "STRING ARE EQUAL$" MSG3 DB "STRING ARE NOT EQUAL$" LINE DW 10,13, '$' STR1 DW 20 DUP('$') STR2 DW 20 DUP This video is about, String comparison in assembly or How to compare two strings in assembly. ---This video is based on the que Apr 13, 2020 · To compare two strings compare each character of one string with the corresponding character of the other. In your case of BYTE strings the relevant OpCode is CMPSB. String Functions in Assembly Language Unfortunately, I cannot provide a direct translation of the given Go code to Assembly Language. String operations allow copying, searching, storing, and comparing strings of characters in memory. i tried used (cmpsb) instruction Nov 28, 2010 · Assembly Language character and string operations summary This web page examines string and character instructions in assembly language. Oct 14, 2022 · I am trying to compare the values of 2 variables to each other in assembly. Let's take a look at an example: Question: 1. Apr 13, 2019 · Ok, c strings store 8-bit values, not 16 bits. Nov 8, 2015 · There are 2 major conventions for storing strings in memory: Explicit-length strings (pointer + length) like C++ std::string, and implicit length strings where you just have a pointer, and the end of string is marked by a sentinel / terminator. The cmpsb is to compare one byte at a time and cmpsw will compare two bytes at a time. They can move strings, compare strings, search for a specific value within a string, initialize a string to a fixed value, and do other primitive operations on strings. 12 - comments and indentation, 12- successfully comparing the 13. Input Two Number and Check Given Number are Equal or Not Equal in Assembly Language - 28 Nov 7, 2025 · Task Demonstrate how to compare two strings from within the language and how to achieve a lexical comparison. The String manipulation instructions are as follows. COMPARING A SPECIFIC CHARACTER WITH INPUT|| Assembly Language Programming || English || emu8086 Krishno Dey 1. It's just a sequence of bytes, whatever meaning you like to assign to it. (Like C char* that uses a 0 byte, or DOS string-print functions that use '$' as a terminator. Instructions like MOVSB, STOSB, LODSB, CMPSB operate on bytes or words in strings and update index registers accordingly I have a bit of experience with C++ and Java but I'm very new to assembly.  The program should:h) Use Real Mode Programmingi) Use Indirect Addressing Modej) Use Irvine16 library for Outputk) Two strings must be assigned within the definition of the strings We would like to show you a description here but the site won’t allow us. Oct 22, 2023 · 11. Please subscribe a Nov 11, 2025 · Friends ఈ video లో Compare the string using string instructions (ALP) Assembly Language Program గురించి Explain చేస్తాను అదేవిదంగా ఈ Program The cmps instruction compares two strings. I have no idea how to compare these two Jul 14, 2009 · The assembler does have to do anything; it is the responsibility of the program to write the instructions one after another. However, machine language is too obscure and complex for using in software development. I want to compare the variables to each other. The direction flag (DF) determines whether string operations proceed from left to right or right to left. I've tried using brackets on each regist May 28, 2021 · Chapter 4 - ALP to Compare two strings using string Instructions SAMARTH_CAMPUS 13. This is because when string is passed in the function it creates a copy of itself in stack. either Learn how to compare strings in C using the strcmp function. Jul 23, 2025 · In C, strcmp () is a built-in library function used to compare two strings lexicographically. . The instruction set does not allow it. The document discusses string operations in 8086 assembly language. They use RDI and RSI. Here, the source operands should be symbols that indicate the size and location of the source values. DATA SEGMENT NUM1 DB 50 NUM2 DB 45 DATA ENDS CODE SE Sep 30, 2015 · How do I compare two strings in assembly (nasm) Asked 9 years, 7 months ago Modified 9 years, 7 months ago Viewed 5k times So comparisons in assembly are essentially subtraction and compare the difference to zero if greater then 0 the first number is bigger, of less than zero then the second number is zero and if the difference equals 0 then both numbers are equal. And I don't know how to write it in assembly language (I use NASM) String is a group of bytes/words and their memory is always allocated in a sequential order. I have a school project to finish and I need to write a simple program in assembly language. oiwtto tlmafx semueg aaqqu cssz gmgdap fbypxmz cndjai buok ngvvz fvy gmdiuz eofovte qjpwut vhel