C modulo array. I noticed that lots of solutions had issues on the x axis array index because of subtraction errors, etc. 0 out of 5 stars based on 3 reviews. It's used to convert the value out of the hash function into an index into the array. I've written a modulus-type program (using std::vector). What does this mean? 14 % 4 is 2, and -14 % 4 is -2. How do I go about doing that using modulo operation? Using C++, the code below works for displ The C++ Modulus Operator [mod or % operator] - The C++ language provides a built-in mechanism, the modulus operator (mod or %), that computes the remainder that results from performing integer division. Unfortunately, C++ doesn’t implement a proper modulus that still works correctly for negative integers. Modular Arithmetic Operations The modulo operator (denoted as % in most programming languages) returns the remainder after the division of one number by another. Edited: I have a big number that C does not have a type for it natively. See this: typedef struct{ u_int8_t * data; u_int16_t length; }UB This probably does not correspond with the precedence of the % operator. We‘ll […] Customers gave dB Technologies DVA T12 Modulo Array Activo 12" 5. In C programming, the modulus operator (%) is used to find the remainder when one number is divided by another. Divide the product by the modulus M. This is what it looks like (example program o Array - Sort By Modulo array in C Asked 12 years, 4 months ago Modified 12 years, 4 months ago Viewed 2k times For the purpose of pointer arithmetic, a pointer to an object that is not an element of any array is treated as a pointer to the first element of an array of size 1. This property links multiplication and addition in modular arithmetic. I'am using new and old to wrap around the array using the modulus operator. The normal way to create such modulo-n sequences is to increase a counter variable Write and run your C programming code using our online compiler. Changing the index type to int doesn't improve things. Hashing: In certain hashing algorithms, the modulus operator is used to map keys to indices in an array. For example, the modulo operator allows creating repeating sequences of non-negative numbers [0, 1, …, n-1] that can be used to build circular arrays or other data structures that reuse array elements when the end of the array is reached. The subtraction and modulo should wrap the index around to the end of the array. I think the cleanest solution is indeed using if to take care of all cases properly. This MATLAB function returns the remainder after division of a by m, where a is the dividend and m is the divisor. 3 days ago · Whether you're checking for even numbers or cycling through array indices, knowing how to use the modulo operator can enhance your coding skills. Learn practical examples and enhance your coding skills with clear explanations and code snippets. All the programs on this page are tested and should work on all platforms. 6 For modulus, -1 would be a wrong answer. Have a look at this for a nice overview on how different programming languages implement the modulo operator. The page contains examples on basic concepts of C programming. I would bet that this is its formal name in the ANSI C & C++ specifications, and that abuse of terminology has crept in. Some languages (like Ada) have even two modulo operators (rem and mod), while others allow to control the behavior at run-time (Perl: ‘use integer’). If i have a char pointer, say char *ptr, that holds the address of a single ascii character, and want to use the modulo operator on that address, how do i do so? Whenever I try and do this with a b The modulo operator (%) is a foundational concept for anyone learning C++, but it‘s also easily misunderstood. A is the dividend Q is the quotient B is the divisor R is the remainder The modulo operator (mod) helps us focus on the remainder: A mod B = R Example: 1 3 5 = 2 r e m a i n d e r 3 513 = 2 remainder 3 13mod 5=3 So, dividing 13 by 5 gives a remainder of 3 So, in modular arithmetic, numbers are reduced within a certain range, defined by the modulus. I can write the program int a = 3; int b = 4; Console. With these operators, you can add, subtract, multiply, or divide values, and calculate the remainder (modulus) of a division operation. It evaluates to the rest of a division of two integer types, for example 7 % 4 evaluates to 3. This creates precision problems once you get past the highest power of ten that can be represented as double. Last year there were a number of solutions that used this trick and it works in a lot of languages. I am trying to understand how to repeat loops using the mod operator. Enjoy additional features like code sharing, dark mode, and support for multiple languages. The fastest MOD algorithm in C++ for extremely large uint_64_t numbers stored in an array Asked 1 year, 3 months ago Modified 1 year, 3 months ago Viewed 128 times This module defines an object type which can compactly represent an array of basic values: characters, integers, floating-point numbers. I hope this article helps you understand the modulo operator and how to apply it effectively in your projects! Mar 12, 2025 · In this article, we will explore how to use the modulo operator in C, providing clear examples and explanations to help you grasp this essential concept. I have minimize cost of calculating modulus in C. Modulo Trick Archived post. Still others (like C90 and C++98) leave it as ‘implementation-defined’. I decided to make a short lesson on using modulo to loop over an array repeatedly. I would like to do this with the modulus operat This article introduces how to use the modulo operator in C++, covering its applications in checking even or odd numbers, implementing cyclic behavior, and utilizing it in algorithms. Essentially i am trying to test if a number is divisible by 4. That's not the mathematical modulus operator, mind you, because in modulus arithmetics a mod b by definition evaluates to a non-negative value for any value of a and any positive The integer modulo operator is widely used in different contexts. Then, you'll want to either hard-code the modulus, or put it in as a compile-time constant. Previously, I was looping over the whole array, so each time an index was updated, I could simply test its value with a mod operation using the length of the array, and reset if necessary. I have to use the Modulus operator to determine the even numbers within the array. ) It is a system of arithmetic for integers, where numbers "wrap around" upon reaching a certain value, known as the modulus. Since we are doing modular arithmetic, we want to reduce each intermediate result modulo 11: \ [ \begin {array} {lclcrcrr@ {\quad\pmod {11}}} 5 &= & 5 & & & & & \text { (mod 11)} \\ 5^2 &= & 25 &\equiv& 3 & & & \text { (mod 11)} \\ 5^4 &\equiv& 3^2 &= & 9 &=& -2 & \text { (mod 11)} \\ 5^8 &\equiv& 9^2 &\equiv& (-2)^2 &=& 4 & \text { (mod 11 . If you have two strings, "abc" and "defgh", how can % be used to loop through abc, repeating it until the end of defgh is reac The best way to learn C programming is by practicing examples. The Modulo operation, represented by the '%' symbol in C++, is often used in a wide array of programming situations such as creating circular arrays, generating random numbers, and more. The answer is easy to compute: divide 11 by 3 and take the remainder: 2. The addition operator concatenates elements. C's % operator is a remainder operator not a modulus operator though — and for remainder, either 10 or -1 is allowable. That's because the modulo operation is ambiguous for negative values and C++ has chosen an interpretation that doesn't guarantee non-negative results. Nov 26, 2025 · This blog dives deep into the problem of negative modulo results in C/C++, explains why positive modulo is critical for array indexing, and presents the fastest methods to compute positive modulo—optimized for performance-critical code. Fixed the way you convert an array of digits to a number - your code used pow, and treated digits at higher indexes as higher-order digits. C++ modulus operator circular array Asked 11 years, 9 months ago Modified 11 years, 9 months ago Viewed 4k times C++ Modulus Operator - Modulus operator returns reminder of the division operation. In this comprehensive 2,500+ word guide, we‘ll fully demystify modulo to give you deep mastery over remainder operations in your C++ programming. But apparently, I've got the modulo calculations wrong and I don't know how to fix them. Understanding modulo will level up your ability to write idiomatic C code. The number after the operator is called modulus. You'll get much better performance that way than whatever tricks you can play with the sign. If y is positive, then x % y repeats every y steps, and I use that to cycle through arrays and ring buffers. In C++, the symbol for the modulus operator is the percent sign (`%`). How does 3 mod 4 = 3??? I can't figure out how this is getting computed this way. We‘ll cover modulo basics and syntax, tackle some illuminating code examples, and debunk common misconceptions. The modulo division operator produces the remainder of an integer division which is also called the modulus of the operation. In JavaScript the modulo operator is %. (If the hash table size is a power of two, the modulus could be done with a bit-mask, but it's still a modulus operation. Let's say that I need to format the output of an array to display a fixed number of elements per line. say I have a number x and n is the number which will divide x when n == 65536 (which happens to be 2^16): mod = x % n (11 assembly instructions 6 One use for the modulus operation is when making a hash table. We can visualize a two-dimensional array as one-dimensional arrays stacked vertically forming a table with 'm' rows and 'n' columns. Calculating Modular Multiplication To calculate modular multiplication, follow these steps: Multiply the two integers a and b. I have to use a char array to hold it. But how would you compute this in a programming language like C or C++? It's not hard to come up with a formula, but the language provides a built-in mechanism, the modulus operator (' % '), that computes the remainder that results from performing integer division. Sistema Acústico Tipo de parlante: Módulo line array activo de 3 vías tri-amplificado Transductores: 1 × Woofer de 12″ con bobina de voz de 3″ 2 × 16 C++ has the % operator, occasionally and misleadingly named "the modulus" operator. As an example, I create a 32-byte array. You are advised to take the references from these examples and try them on your own. Você vai aprender: Diferença entre arrays unidimensionais e multidimensionais Operações úteis da classe `Array`, como `Sort` e `Reverse` Como o Unity exibe arrays dos scripts diretamente no Articles and Tech Tutorials from Andy Van Slaars Powerful N-dimensional arrays Fast and versatile, the NumPy vectorization, indexing, and broadcasting concepts are the de-facto standards of array computing today. Importantly, in JavaScript the return value is signed. If y is a power of two, then x % y can often be compiled into a bitmask operation, and the compiler does that in 1 or 2 instructions. The result of the expression n mod m n mod m is known as n n 's residue modulo m m. SIZE should always be at least 55, but I want to round up to 64 to speed up the modulo. remainder and C’s remainder, which compute the IEEE remainder, which are the complement to round(x1 / x2). I need to create an algorithm implemented in C that do modulo arithmetic between an arbitrary number of bytes and one byte. It represents a large number up to 2 ^ 256. C: modulo operator % % is the modulo operator. The MATLAB rem function and or the C % operator which is the complement to int(x1 / x2). The user inputs a number, and the program displays a modulus grid pertaining to that number. WriteLine(a % b); The answer I get is 3. The value m m after the modulo operator is known as the modulus. Arrays are mutable sequence types and behave very much like I am trying to manipulate a two-dimensional array so that I can check if the indexes "next to" them are in a certain state. I would like to keep a running average of a specified number by the user. Jul 12, 2025 · In C or C++, the modulo operator (also known as the modulus operator), denoted by %, is an arithmetic operator. First of all, a quick definition: the modulo operator gives the remainder of a division of one number by another. To fix this problem, we add numRows to i before taking the modulo numRows. Animation and Graphics: In animation and graphics programming, modulus can be used to create repeating patterns or to ensure that values wrap around within a specific range. This ensures that we're always taking the modulo of a positive number. If I have an N x N grid, that looks like I was solving following problem on LCM : Calculate LCM of N numbers modulo 1000000007 My approach : typedef unsigned long long ull; const ull mod=1000000007; ull A[10009]; /*Euclidean GCD*/ ull g I have to make a program print the even numbers from my array and output the even number and the corresponding letter that goes with that number. The C and C++ standards don't specify the sign of the modulus when the first number is negative (until C++11, which does guarantee it will be negative, which is what most compilers were already doing). Browse customer photos and videos on Judge. 23 modulo 4 --> 3 22 modulo 4 --> 2 21 modulo 4 --> 1 20 modulo 4 --> 0 19 modulo 4 --> 3 18 modulo 4 --> 2 I would have expected a number that i can make sense of. The modulo operator unlocks many capabilities in C around remainders, repetitions, sequences, and arrays. Distributivity: (a × (b+c)) mod M = ( (a×b) mod M + (a × c) mod M) mod M. It’s an essential arithmetic operator, especially in situations where you need to work with remainders, such as checking if a number is divisible by another number or performing operations in cycles (like rotating through an array). In programming, the use of the modulus operator can be essential for tasks such as determining even or odd numbers, cycling through arrays, and implementing more complex algorithms like those in cryptography. Whether you’re a beginner or looking to refresh your knowledge, this guide will serve as an invaluable resource. I have just noticed that Bjarne Stroustrup labels % as the remainder operator, not the modulo operator. Perfect for beginners and experienced programmers alike. Módulo line array activo de 3 vías con un woofer de 12″ Pulgadas con DSP Integrado. Here is an implementation in C++: Learn C code modulus operations with examples, including modulo arithmetic, remainder calculation, and integer division, to master mathematical functions in programming. : Python’s math. You may also sometimes see the notation expr1 ≡ expr2 (mod m) e x p r 1 ≡ e x p r 2 (mod m). In its most elementary form, it is arithmetic done with a count that resets itself to zero every time a certain whole number N greater than one, known as the modulus (mod), has been reached. me. (PS. 2D Array - Two Dimensional 3D Array - Three Dimensional 2D Arrays in C A two-dimensional array or 2D array is the simplest form of the multidimensional array. In this tutorial, we learn the syntax, and the list of allowed datatypes for modulus operator in C++, with example C++ programs. Want to learn C Programming by writing code yourself? Enroll in our Interactive C Course for FREE. In particular the STL has the modulus<> functor in the <functional> header. In general, if you want to step back more than 1, you need to make sure that you add enough so that the first operand of the modulo operation is >= 0. Finding the modular inverse for array of numbers modulo m Suppose we are given an array and we want to find modular inverse for all numbers in it (all of them are invertible). 2ap9, aenlmd, xbow4u, pfe5, 6geoq, estk8, n06o, asbvxo, gds05c, oea6y,