# Questions tagged [integer]

Use this tag for questions about using, storing or manipulating integral values of all types and sizes, including concerns about overflow. Not for code that casually happens to use integers.

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### Prime factors and perfect square

I want to convert an integer to a perfect square by multiplying it by some number. That number is the product of all the prime factors of the number which not appear an even number of times. Example ...
363 views

### Adding thousand separator to various number types

Am making a pure .net library with helper functions (GitHub). However I wanted to have a thousand separator for all number types and here is what I am currently doing ...
124 views

### Functions to handle big numbers in C

I'm working to implement some simple bigint functions for addition, multiplication and powers. They work correctly but the larger the numbers the longer the time it takes. For example 210000 takes a ...
754 views

### atoi implementation in C

I'm looking for feedback on my atoi implementation here in C. Any feedback would great. I made my own atoi for fun and to learn ...
264 views

### Encoding 0/1 bits to 0/255 bytes in C++

I need to map a sequence of bits that represents a float into a sequence of bytes by this rule: the value 1 maps to the value 255 and the value 0 maps to the value 0. This is the code I have now: <...
504 views

### Change Arithmetic Right Shift to Logical Right Shift

The following code is a solution to a textbook (Bryant&O'Hallaron: Computer Systems A programmer's Perspective 2nd Ed) problem in bit-level data manipulation (attempted for the challenge, not a ...
75 views

### Breaking a 32-bit value into bytes for an ArrayList

I am very new to Java and its collections and I'm trying to figure out "best" way to populate an ArrayList<Byte> in Java. In particular, I'm trying to take a ...
4k views

### Int to Enum Extension Method

As you know, converting an int to an enum is straightforward. Doing it generically with type/range checking isn't. I looked for a reusable example since this seems like a common situation but did not ...
93 views

### BigInteger check in C from a string

I have started to learn C. At the time of writing I don't know anything about the language. The following I wrote today in a few hours. Though I do have a lot of programming experience, I find C hard ...
59 views

### Calculating the volume of a box

I've been studying more C using C Programming: A Modern Approach: A Modern Approach 2nd Edition by K.N. King as well as reading the comp.lang.c FAQ and the Code Review section here on Stack Exchange ...
145 views

### Test whether a number is a Harshad Number

A little code I wrote that will check if the entered 4-digit number is Harshad or not (Harshad number is one which divided by the sum of its digits will leave no remainder, special Harshad is the same ...
181 views

### Addition function for two Big Integers represented as std::string

This function is from my attempt to write a Big Integer class in C++. Below, I have a simple addition function. It takes two strings of arbitrary length which contains only digits (no '-' sign as ...
84 views

### Expressing positive integers as the sum of different charming numbers

In a practice academic interview of mine, we discussed question six, round one, of the United Kingdom Mathematics Trust's 2015 British Mathematical Olympiad. Which states: A positive integer is ...
138 views

### C++ big unsigned integer class

Here is a big unsigned integer type I intend to use for learning and "fun" with cryptography. It uses a std::vector for storing blocks of unsigned integers, the ...
29k views

### Int overflow check in Java

I have a piece of code that takes a couple of integers and check if performing an addition on the inputs would result in an overflow. I was wondering if this code is SOLID: ...
10k views

### An exception-safe wrapper for std::stoi

std::stoi may throw exceptions so it needs to be surrounded by try/catch. In applications where std::stoi may be used ...
285 views

My purpose is to add two __m512i variables (c = a + b) as efficiently as possible. To do so, I'd like to use the _addcarryx_u64 ...
3k views

### Diffie-Hellman in JavaScript

Diffie-Hellman is a key exchange that allows 2 people to share a symmetric key without interaction beforehand. First, a person shares an equation; in this case, we use: $$3^x \mod{17}$$ Next, each ...
13k views

### BigInteger implementation in C, supporting addition and multiplication

I've implemented adding and multiplying arbitrary precision integers. Also available as a gist. ...
2k views

### Unsigned integer division ARM Cortex-M0+ Assembly

I am writing a subroutine for unsigned integer division in Assembly. I will call the subroutine DIVU. Inputs: R1 will be the ...
115 views

### Hash function in C for sets and associative arrays

I wrote a non-cryptographic hash function in C, which I am hoping might be suitable for use in an implementation of hash sets or hash maps. ...
44 views

### Extract and divide algorithm implementation in Elixir

I just started learning Elixir and stumbled upon this challenge over on Programming Puzzles & Code Golf. It is a well-suited task for beginners, so I chose to give it a go (to be clear, give it a ...
16k views

### Separate numbers with commas

How should I approach refactoring this code? ...
82 views

### Find the first palindrome larger than the given number

Question Input number of test cases. Input each test case and output its next palindrome number. Link: https://www.spoj.com/problems/PALIN/ Language Used: C++14 (gcc 6.3) My code ...
385 views

### Reading lines of integers into a list of lists

I have a text file containing integers in different lines which I want to read into a list of lists. So 01 11 14 45 50 09 should become ...
141 views

### Printing 64-bit decimal numbers in freestanding environment

I need to print signed 64-bit numbers in decimal form. Program runs in freestanding environment (no C library available, libgcc may be unavailable too, or may not work correctly). So I can't use ...
209 views

### Custom integer parser optimized for performance

I want an integer parser so fast it risks discovering time travel. I'm stuck in C# for a language, but that doesn't mean I can't try to use c++. So I wrote the following: The best I could do ...
130 views

### Safely & portably read a value into a predefined integral type of varying size like mode_t

I need to read a value from a text file and put it into a predefined type, in this particular case mode_t. This typedef can have a variety of types underlying it, ...
3k views

### reinterpret_cast vs bit shifts for extracting 32-bit integers from bytes, with either endianness [closed]

I've written some simple helper functions that read data types from a vector of bytes (binary files) and having a tough time deciding which route to go. Method 1 : reinterpret_cast ...
2k views

### Computing the integer square root of large numbers

The "integer square root" of a non-negative integer $n$ is defined as the largest integer not greater than $\sqrt{n}$:  \operatorname{isqrt}(n) = \lfloor \sqrt{n} \rfloor = \max \{ k \in \...
8k views

I would like to give an Integer to whatever demands it. For that I use the following code ...
205 views

### (Almost) arbitrary base ints with decorated methods

After reading this question about returning the "next" string in some alphabet (the digits, followed by upper and lowercase ASCII letters) using Java, I thought, well that's just counting, so why not ...
744 views

I have a function add that adds two lists of integers: add [1, 2] [4, 5, 8] == [4, 7, 0] add [9, 8, 9] [1, 3] == [1, 0, 0, 2] ...
84 views

### Check whether an integer's leftmost bits are ones in Rust

I'm trying to validate if an integer represents a valid IPv6 mask, which boils down to checking if all the left-most bits of an u128 are 1s, and all the right-most bits are 0s. For instance: ...
723 views

### 'StrictInt' Python object class that prohibits casting numbers with non-integer components to int

Inspired by and created because of python3 utility: convert safely to int and driven partly by the 'refactor' in my answer. The aforementioned question and my answer drove me to go and do a thing ...
169 views

### Detecting over-/underflow for uint64+int64

I am trying to write a function in Go which adds an uint64 value and an int64 value and which detects whether the result can be ...
1k views

### Convert unsigned Integer to ASCII in x86 assembly

This is my best effort to code an x86 32 bits to get an unsigned int (4 bytes) and convert it into a string. My strategy was successively divide the number by ten and fulfill the remainder of the <...
529 views

### Recursive implementation of integer partition without re-arrangement

Problem: Integer partition without re-arrangement Input: An arrangement S of nonnegative numbers {s1, . . . , sn} and an integer ...
6k views

### Tough List Comprehension Split Letters and Numbers

So, another challenge from my professor. I've finished it, but wanted to get some feedback, and see how other people might work this problem. Assume you have a string, such as "Hello 34215 World ...
8k views

### Big integer class in C++

I have been trying my hand a bit at creating a big integer class in C++. This is a continuation of a homework assignment. The class stores a big integer in a double linked list. Each slot contains 8 ...
225 views

### Caching an integer - distinguishing no value from zero

I would like to store an integer value in the application cache. The GetOrSet method should always return an int, and never be null. If there is no cached value, ...
15k views

### Implementation of atoi()

I implemented the atoi() function! Here is my code: ...
71 views

### C++ library with tools for (arithmetic) type manipulation and mixing

Broken out from a previous question (C++17 saturating integer (arithmetic) type library) is a small C++17 header-only library to deal with issues that arise working with arithmetic where signed, ...
2k views

### C++17 saturating integer (arithmetic) type library

I wrote a C++ library to provide extra signed and unsigned integer types that saturate in overflow situations. It's in proof of concept stage and I'd love to get some feedback on it. A short usage ...
20k views

### Checking if a number is power of 2 or not

This is my solution in Java and I need your opinion: ...
19k views

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### Printing limits of Integral Types in C

I intend to demonstrate the proper way to use format specifiers for different data types and also display the respective limits. This is meant to be an example. ...
3k views

### Reversing the bits of a 32-bit integer

Here is my code: ...