Questions tagged [c++]
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. This tag should be used for any question which requires knowledge or expertise with the C++ programming language. This is a general tag which is used for any of the C++ language standards (C++98, C++11, C++17, etc.). The question should identify the compiler being used, the operating system, and which of the C++ standards is being targeted.
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Dijkstra path finding in C# is 15x slower than C++ version
I'm implementing Dijkstra's algorithm with a priority queue for a game I'm developing in Unity with C#. I was a bit disappointed with the performance, so I decided to port the code to C++ and see if ...
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votes
5
answers
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Basic Pokedex in C++
I recently started learning C++ about a week ago, and I made a bit of progress. In honor of Pokemon Go releasing, I decided to make a Pokedex with the original 151 Pokemon. So far I have 120 or so of ...
- 1,431
117
votes
11
answers
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Fastest way to clamp an integer to the range 0-255
I'm working on some image processing code that can generate pixel values outside of the normal range of 0 to 255, and I'd like to clamp them back into the valid range. I know that there are saturating ...
- 1,856
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votes
16
answers
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Outputting the names of cars, without repetitions, with the number of occurrences in order of decreasing repetitions
A short while ago, I have submitted a coding exercise to a
potential employer. The response came back the next
morning and you can guess what it was from the subject
of this post.
I am not ...
- 1,141
74
votes
8
answers
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Open, write and close a file
I have a small 10-liner function that writes some data to a file using an std::ofstream. I did not explicitly call .close() at ...
- 1,118
71
votes
6
answers
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infix_iterator code
I've previously posted this on Stack Overflow, and am considering submitting it to Boost for wider distribution, but thought perhaps it would be best to put it up here for peer review first, and see ...
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votes
4
answers
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Seed std::mt19937 from std::random_device
Many people seed their Mersenne Twister engines like this:
std::mt19937 rng(std::random_device{}());
However, this only provides a single ...
- 793
54
votes
6
answers
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ASCII text-based RPG game in C++
I started to make a C++ RPG game just for fun. It does have quests but it isn't just one long adventure that lasts like 30 minutes. I would like to know what I did well on and things on which I can do ...
- 643
54
votes
6
answers
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Simple integer range for C++11 range-based for loops
I'm really tired of having to type
for (int iSomething = rangeBegin; iSomething < rangeEnd; ++iSomething)
{
...
}
whenever I want to iterate over an ...
- 787
54
votes
2
answers
4k
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Named operators in C++
A post by Yakk alerted me to the idea of named operators in C++. This look splendid (albeit very unorthodox). For instance, the following code can be made to compile trivially:
...
- 6,588
51
votes
3
answers
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shared_ptr and FILE for wrapping cstdio (update: also dlfcn.h)
Even in the presence of <fstream>, there may be reason for using the <cstdio> file interface. I was wondering if ...
- 1,193
49
votes
1
answer
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Yet another C++ JSON parser
This is a framework for a JSON parser I put together last night.
Any comments appreciated.
JsonLexer.l: Breaks the input into lexemes
JsonParser.y: Understands the language syntax
JsonParser.h: ...
- 94.3k
48
votes
7
answers
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Mandelbrot image generator and viewer
This is a C++ program which outputs a Mandelbrot fractal image in a graphics window and lets the user zoom and pan around the image, generating a new image each time the user does so. I'm using SFML ...
- 581
43
votes
7
answers
45k
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Conway's Game of Life in C++
This is my attempt at Conway's Game of Life. It works, and it's the most complicated program I've made to date. I'm sure it's pretty poorly done. Any ideas on how I can improve on it?
...
- 974
43
votes
5
answers
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Parallel sieve of Eratosthenes
For the first time, I tried to use threads by myself in order to implement a parallel sieve of Eratosthenes. The trick is that each time a prime is found, a thread is spawned to eliminate all the ...
- 19.9k
43
votes
2
answers
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Snake game in C++
This is my version of the Snake game, written in C++. How could it be improved, and what general advice would be useful for future projects?
...
- 950
42
votes
12
answers
10k
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Efficiently squaring each element in a sorted array, keeping it sorted
The other day I was asked the following question during an interview:
Given a sorted array, how would you square each element of this array, while keeping it sorted?
I froze up and wrote a ...
- 551
41
votes
4
answers
22k
views
Boolean enums: improved clarity or just overkill? [closed]
Suppose we are writing a GUI toolkit in C++ (though this question may also apply to other languages). We have a button class with a member function hide, which ...
- 664
41
votes
9
answers
124k
views
Converting between std::wstring and std::string
While researching ways to convert back and forth between std::wstring and std::string, I found this conversation on the MSDN ...
- 553
40
votes
1
answer
4k
views
Recursive shared_mutex implementation
I found myself in need of a Readers-Writer mutex. With C++17 TR2 support not yet available in our compiler, I set out to implement std::shared_mutex so that we have ...
- 16.5k
38
votes
5
answers
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Easier user input in C++
A more proper version of this utility can be found at the following link here: Giveth me thy easier user input in C++ - follow up.
I've always been a little bothered by the fact, that in order to get ...
- 15.8k
38
votes
6
answers
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views
38
votes
6
answers
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Parser written in PHP is 5.6x faster than the same C++ program in a similar test (g++ 4.8.5)
I'm absolutely dumbfounded by this. I was trying to demonstrate to myself how much faster C++ is than even modern PHP. I ran a simple CSV parsing program in both that have the same output. The CSV ...
- 481
37
votes
8
answers
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Thread Pool C++ Implementation
I have been working on this thread pool for awhile to make it as simple to use as possible. I need some tips on improving performance, and some good ways to test its performance. I was wondering if ...
- 492
37
votes
6
answers
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AES Implementation in C++
I've implemented AES (128, 192 and 256) in C++ and I'm looking to improve the code to make it not "DIY-crypto-bad", if at all possible. I've also been trying to optimize my code, and so far I've ...
- 583
36
votes
9
answers
7k
views
Solving the Lazy Hobo Riddle
I would like help in optimizing this calculation, which is from the Lazy Hobo Riddle:
There once were 4 hoboes travelling across the country. During their
journey, they ran short on funds, so ...
user54410
36
votes
6
answers
10k
views
Printing lyrics of 99 Bottles of Beer
I wrote a C++ program for 99 Bottles of Beer, but it's kind of messy. Is there any way I can make it short and cleaner and more easier to read?
...
- 547
34
votes
2
answers
68k
views
A multi-threaded Producer Consumer with C++11
I am trying to learn concurrent programming in C++11. I tried to write code for a classic producer consumer concurrency problem. Would you please review and make any comments about it?
...
- 391
34
votes
3
answers
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LinkedList with Node implementation
Below is my implementation of templated Node and LinkedList classes. I would really appreciate it if someone would give me ...
33
votes
9
answers
7k
views
Simple n-body class in C++
As part of my training, I implemented a n-body class in C++ to simulate gravitational interaction of bodies and to get more familiar with features that C++ offers such as object oriented programming.
...
- 1,125
33
votes
1
answer
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JSON Serializer
Carrying on from:
Yet another C++ Json Parser
Yet another C++ Json Parser (Recursive)
All the code is available from git hub: ThorsSerializer but only reviewing a small section here.
The idea is ...
- 94.3k
32
votes
10
answers
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Sorting large 1GB file with 100 millions numbers using merge sort
My task is to sort 1GB file with 100 million numbers using merge sort without recursion. My idea is to split file into 4 pieces, then to 2 and at the end to one file.
...
- 459
32
votes
2
answers
5k
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Tic Tac Toe C++
I made this Tic Tac Toe game and I would like to know your opinion and what can be improved. I also want advice about making it check if someone wins. I'm 10th grader, so I still need to learn a lot.
...
- 321
32
votes
4
answers
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Extending Sieve of Eratosthenes beyond a billion
For MAX value of 1000000000 (\$10^9\$), it takes about 45 seconds to reach the line where it prints "done". How can I speed this ...
- 823
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votes
4
answers
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Standardly deviated Fibonacci
I'm new to C++ (about 4 weeks with no prior programming experience in other languages) and am writing a program that's supposed to do the following:
Define an array of 100 sequential numbers of type <...
- 321
32
votes
6
answers
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Aliens at the train
I solved this problem on SPOJ:
The aliens have arrived to Earth and everything is in harmony, the two
races can live together. However, one specific Female Alien does not
want to see humans on ...
32
votes
2
answers
7k
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Lexer+Parser code for my "Reedoo" programming language
I've been working on my own programming language, as a hobby for the past couple of months now, called Reedoo. It is implemented in pure C++ 11 and uses only the libraries that come with C++; no ...
- 547
31
votes
4
answers
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Validity of doubly linked list
I am currently in a data-structures class. The professor will be providing a singly linked list. I wanted to make a doubly linked list to "learn" how to do it. I tested it and I think it works. After ...
- 531
31
votes
2
answers
1k
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Dynamically call lambda based on stream input
Some context: I have code that looks like this (minor issue noted here):
...
- 94.3k
31
votes
3
answers
28k
views
Quadtree implementation
I've implemented a quadtree in C++. Ignore any apparent similarity to the pseudocode on Wikipedia, it's all in your head, I swear.
How can I improve it? Algorithm speed/space improvements, any extra ...
- 2,226
31
votes
1
answer
3k
views
Yet another 'any' class implementation, named 'some'
This is a follow-up of 'any' class implementation. After posting my answer, I kept working on the code towards parameterizing with respect to memory management as I had promised. I ended up in some ...
- 2,274
30
votes
3
answers
10k
views
Keeping track of the tennis score
I'm trying to get hired by some company and they gave me a simple remote test to take at home so they can judge my coding skills.
It's a really simple problem based on the website HackerRank. It's a ...
30
votes
5
answers
18k
views
A Fraction class in C++
I am trying to learn clear and concise C++. Currently I'm learning classes in school, and to practice I have made a Fraction class.
I'd appreciate any help regarding style, cleanliness or anything ...
- 403
30
votes
2
answers
57k
views
Custom iterator for a linked list class
I have made a LinkedList class. This is a singly-linked-list and I want to make a forward_iterator for this class without using ...
- 403
30
votes
3
answers
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"Zip-like" functionality with C++11's range-based for-loop
My goal was to get the following code to work:
...
- 423
30
votes
1
answer
22k
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SIMD matrix multiplication
I recently started toying with SIMD and came up with the following code for matrix multiplication.
First I attempted to implement it using SIMD the same way I did in SISD, just using SIMD for things ...
- 451
29
votes
4
answers
7k
views
Is it Friday yet?
This is the first program that I have written in my C++ saga that I actually think is useful. The description for this assignment is kinda long and mundane though:
Write a program that inputs a ...
- 21.8k
29
votes
4
answers
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views
Project Euler 001 in C++
I come from a C background and have now just begun C++.
This also means that I am not focussing on the algorithm, but more on C++ idioms.
Description:
If we list all the natural numbers below 10 ...
- 1,079
29
votes
3
answers
59k
views
Impossibly fast delegate in C++11
This legendary C++ delegate article can be easily converted into C++11, without the need for fancy preprocessor magic in the original. I'd like to know if I got all the necessary C++11 nuances right. ...
28
votes
5
answers
8k
views
C++ logging library
I am creating a logging library in C++, and I wanted your opinion on code quality and performance within some methods.
You may ask why yet another logger - the answer is simple. This logging library ...
- 361