Trending questions in C++

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How to use enums in C++

Suppose we have an enum like the following: enum Days ...READ MORE

Jul 7, 2022 in C++ by Nicholas
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424 views
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1 answer

Is there an easy way to make a min heap in C++?

Use make heap() and its buddies from algorithm>, or priority queue from queue>.  Make heap and friends are used by priority queue. #include <queue> // functional,iostream,ctime,cstdlib using namespace std; int main(int ...READ MORE

Jun 27, 2022 in C++ by Damon
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789 views
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Why doesn't C++ have a garbage collector?

First and foremost, I'm not raising this ...READ MORE

Jul 5, 2022 in C++ by Nicholas
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487 views
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1 answer

What is the difference between std::__gcd and std::gcd?

I done some research about this. The ...READ MORE

Jun 10, 2022 in C++ by Damon
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1,511 views
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Infix to Postfix notation C++

Hello there, Stack.  I'm currently learning C++ and trying to create an RPN converter.  But I'm having difficulties.  Hopefully, I'll be able to describe the issues in detail.  For stacking my operators, I'm using an array.  Let's look at the example "5 + 8."  When it comes down to: else if(infix[i] == '+' or infix[i] == ...READ MORE

Jun 29, 2022 in C++ by Nicholas
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710 views
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1 answer

Vector of Vectors to create matrix

Before accessing any elements, you must first set the vector of vectors to the right size.  You may do it this way: // assumes using std::vector for brevity vector<vector<int>> matrix(RR, ...READ MORE

Jun 16, 2022 in C++ by Damon
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Differences between C++ string == and compare()?

I just read some recommendations on using std::string ...READ MORE

Jul 7, 2022 in C++ by Nicholas
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303 views
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How to choose between map and unordered_map?

Assume I wanted to map data that ...READ MORE

Jul 4, 2022 in C++ by Nicholas
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444 views
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How to access static members of a class?

I'm learning C++ and Qt, but even the simplest code that I copy and paste from a book produces problems. On Ubuntu 10.04, I'm using g++4.4.2 with the QtCreator IDE.  Is there a distinction between the syntax of the g++ compiler and those of other compilers?  When I try to access static members, for example, something always goes wrong. #include <iostream> using namespace std; class A { ...READ MORE

Jul 7, 2022 in C++ by Nicholas
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299 views
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Check if element is in the list (contains)

The simplest and quickest method. You could also ...READ MORE

Jun 2, 2022 in C++ by Damon
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1,741 views
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What does the C++ standard state the size of int, long type to be?

I'm seeking for specific information on the sizes of basic C++ types.  I understand that it is determined by the architecture (16 bits, 32 bits, or 64 bits) and the compiler. But are there any C++ standards? On a 32-bit architecture, I'm using Visual Studio 2008.  This is what I get: char : 1 byte short : 2 ...READ MORE

Jul 7, 2022 in C++ by Nicholas
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243 views
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How to traverse stack in C++?

Is traversing std::stack possible in C++? It is not possible to traverse using the following method.  Because there is no member end in std::stack. std::stack<int> foo; // .. for (__typeof(foo.begin()) it = foo.begin(); ...READ MORE

Jun 1, 2022 in C++ by Nicholas
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1,808 views
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1 answer

Difference between Turbo C++ and Borland C++ compiler [closed]

I will try my best to respond, ...READ MORE

Jun 21, 2022 in C++ by Damon
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920 views
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1 answer

How do I reverse a C++ vector?

The algorithm header has a method std::reverse for this purpose. #include <vector> #include <algorithm> int main() { std::vector<int> ...READ MORE

Jun 27, 2022 in C++ by Damon
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606 views
0 votes
1 answer

please help me with max_element function in c++ stl

You can substitute max for *max eleme ...READ MORE

Jun 27, 2022 in C++ by Damon
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590 views
0 votes
0 answers

What does the C++ standard state the size of int, long type to be?

I'm seeking for specific information on the sizes of basic C++ types.  I understand that it is determined by the architecture (16 bits, 32 bits, or 64 bits) and the compiler. But are there any C++ standards? On a 32-bit architecture, I'm using Visual Studio 2008.  This is what I get: char : 1 byte short : 2 ...READ MORE

Jul 5, 2022 in C++ by Nicholas
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274 views
0 votes
1 answer

How do I erase an element from std::vector<> by index?

You might perform the following to remove a single element: std::vector<int> vec; vec.push_back(6); vec.push_back(-17); vec.push_back(12); // Deletes the second element (vec[1]) vec.erase(std::next(vec.begin())); Alternatively, to remove many elements at once: // ...READ MORE

Jun 10, 2022 in C++ by Damon
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1,307 views
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Reverse a number without converting it to string in C++

I'm attempting to write a programme in C++ to reverse a number. It works well with numbers like 1234, but when I try to enter a number like 5430, it displays 345, and the same with numbers that begin with zero, such as 0234, which displays 432. Could someone please explain how to deal with zeros at the beginning and end of a sentence? I simply need to save the number without converting it to a string. #include<iostream> using namespace std; int main(){ ...READ MORE

Jun 30, 2022 in C++ by Nicholas
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462 views
0 votes
1 answer

Has Windows an integrated built-in C/C++ compiler package?

Microsoft does not offer a compiler or ...READ MORE

Jun 14, 2022 in C++ by Damon
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1,118 views
0 votes
1 answer

C++ string in classes

The std namespace contains the string class. You need change the class to something like this: class Language { public: ...READ MORE

Jun 15, 2022 in C++ by Damon
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1,076 views
0 votes
1 answer

*this vs this in C++

This is a pointer, and *this is a pointer that has been dereferenced. If you had a function that returned this, it would be a pointer to the current object, but a function that returned *this would be a "clone" of the current object, created on the stack unless you defined the method's return type to be a reference. A small application that demonstrates the difference between working with copies and working with references: #include <iostream> class Foo { public: ...READ MORE

Jun 28, 2022 in C++ by Damon
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494 views
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1 answer

What does "#include <iostream>" do?

You must include it in order to read or write to the standard input/output streams. int main( int argc, char * argv[] ...READ MORE

Jun 28, 2022 in C++ by Damon
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468 views
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0 answers

C++ Singleton design pattern

I recently came upon a C++ realization/implementation of the Singleton design pattern.  It looked like this (I took it from a real-life example): // a lot of methods are omitted ...READ MORE

Jul 4, 2022 in C++ by Nicholas
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255 views
0 votes
0 answers

C++ printing boolean, what is displayed?

I print a bool to an output stream like ...READ MORE

Jul 1, 2022 in C++ by Nicholas
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371 views
0 votes
0 answers

Static vs dynamic type checking in C++

I'm curious in the differences between static ...READ MORE

Jul 1, 2022 in C++ by Nicholas
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369 views
0 votes
1 answer

Ceil function: how can we implement it ourselves?

You can disassemble the components of an IEEE754 floating point number and put the logic together yourself: #include <cstring> float my_ceil(float f) { ...READ MORE

Jun 13, 2022 in C++ by Damon
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edited Jun 14, 2022 by Hemant 1,089 views
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1 answer

insert method for doubly linked list C++

I attempted to repair all of your methods, and I believe I succeeded; at least, the current test example prints the proper answer: #include <iostream> #include <vector> using namespace std; struct Node { ...READ MORE

Jun 21, 2022 in C++ by Damon
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745 views
0 votes
0 answers

Deep copy vs Shallow Copy

What's the distinction between deep and shallow ...READ MORE

Jun 29, 2022 in C++ by Nicholas
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409 views
0 votes
0 answers

take string input using char* in C and C++

I'm having trouble accepting a string (actually a character array) as input.  Consider the following declaration: char* s; I have to input a string ...READ MORE

Jul 1, 2022 in C++ by Nicholas
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329 views
0 votes
0 answers

Selection sort in C++ (modified) not working for all cases

I was attempting to tweak the selection sort code in C++ in order to test the results.  My updated code is as follows: #include<bits/stdc++.h> using namespace std; int main() { ...READ MORE

Jun 29, 2022 in C++ by Damon
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377 views
0 votes
1 answer

Is 'If Else' statement indentation important or not in C++? [duplicate]

White space has no effect on the understanding of code in C and C++.  That is not to say that the programmer should be unconcerned about its misuse. The easiest method to demonstrate what the above code truly represents is to specify all of the inferred braces directly, as seen below.  The 'if then' or 'otherwise' clause only affects one line of code in the if statement with no brackets. This is one of the reasons why people strive to insist on 'proper coding standards' to guarantee that other people can clearly grasp the programmer's flow and meaning. while(c != cols) { ...READ MORE

Jun 27, 2022 in C++ by Damon
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430 views
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0 answers

Is the std::set iteration order always ascending according to the C++ specification?

According to what I've read, std::set in ...READ MORE

Jun 29, 2022 in C++ by Nicholas
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372 views
0 votes
0 answers

What is the easiest way to initialize a std::vector with hardcoded elements?

I can make an array and initialise&nb ...READ MORE

Jun 27, 2022 in C++ by Nicholas
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467 views
0 votes
0 answers

Why use #define instead of a variable

What is the purpose of the #define ...READ MORE

Jul 1, 2022 in C++ by Nicholas
• 7,760 points
295 views
0 votes
1 answer

In C++ abs( *a - *b) does not return absolute value of negative number

On the first line, you reallocated *a, and it is now utilising that new value on the second line.  int origa = *a; *a = abs(origa + ...READ MORE

Jun 27, 2022 in C++ by Damon
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525 views
0 votes
0 answers

What is the STL?

I'm not a C++ coder, thus I ...READ MORE

Jun 29, 2022 in C++ by Damon
• 4,960 points
349 views
0 votes
1 answer

Easiest way to convert int to string in C++

std::stoi (and variations for each numeric type) ...READ MORE

Jun 15, 2022 in C++ by Damon
• 4,960 points
922 views
0 votes
1 answer

Binary literals?

Binary literals will be supported in  ...READ MORE

Jun 27, 2022 in C++ by Damon
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492 views
0 votes
0 answers

Difference between set.upper_bound() and upper_bound(set.begin(), set.end()) stl

I discovered that set.upper bound() was quicker ...READ MORE

Jun 29, 2022 in C++ by Damon
• 4,960 points
316 views
0 votes
1 answer

Initializing a two dimensional std::vector

Assume you wish to start a 2D vector, m*n, with a value of 0. We could do it. #include<iostream> int main(){ int ...READ MORE

Jun 27, 2022 in C++ by Damon
• 4,960 points
371 views
0 votes
0 answers

How to use c++ swap function?

It is OK to write swap(a,b); There is an issue when I write swap(&c[0],&d[0]);.  Can anyone explain why? #include<iostream> #include<algorithm> using namespace std; int main(void){ ...READ MORE

Jul 1, 2022 in C++ by Nicholas
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242 views
0 votes
0 answers

How can I get the maximum or minimum value in a vector?

In C++, how can I find the greatest or minimum value in a vector? Is it correct to assume that it would be similar with an array? Do I require an iterator?  I tried max element, but I kept receiving errors. vector<int>::const_iterator it; it = max_element(cloud.begin(), cloud.end()); error: request for ...READ MORE

Jun 27, 2022 in C++ by Nicholas
• 7,760 points
406 views
0 votes
1 answer

The static keyword and its various uses in C++

Static variables exist during the "lifetime" of the translation unit in which they are declared, and: It cannot be accessible from any other translation unit if it is in a namespace scope (i.e. outside of functions and classes).  This is referred to as "internal linking" or "static storage lifetime."  (Except for constexpr, do not do this in headers; otherwise, you would wind up with a different variable in each translation unit, which is really confusing.) If it is a variable in a function, it, like any other local variable, cannot be accessed from outside the function.  (This is the mentioned local) Class members have no limited scope owing to static, but they may be referenced from both the class and an instance (like std::string::npos). locations as code: static std::string namespaceScope = "Hello"; void ...READ MORE

Jun 27, 2022 in C++ by Damon
• 4,960 points
350 views
0 votes
1 answer

What does the explicit keyword mean?

To resolve the parameters to a function, the compiler is permitted to do one implicit conversion.  This implies that the compiler can utilise constructors with a single argument to convert from one type to another to find the correct type for a parameter. Here's an example class with a constructor ...READ MORE

Jun 27, 2022 in C++ by Damon
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349 views
0 votes
0 answers

C++ pointer to objects

Is it always necessary in C++ to  ...READ MORE

Jun 27, 2022 in C++ by Nicholas
• 7,760 points
387 views
0 votes
1 answer

Use of multisets in C++ [duplicate]

Because a multi-set does not need the storage of single-element objects.  You're considering storing anything in a multi-set, such as a string.  But it is not its intended use.  You may use whatever struct you want and compare it to a single element in the struct. As an example: struct PhoneBookEntry { std::string name; ...READ MORE

Jun 27, 2022 in C++ by Damon
• 4,960 points
338 views
0 votes
0 answers

Sorting Characters Of A C++ String

Is there a built-in method for sorting characters in a string, or do I have to construct my own? for instance: string word = "dabc"; I would want to ...READ MORE

Jun 27, 2022 in C++ by Nicholas
• 7,760 points
377 views
0 votes
1 answer

Using :: (scope resolution operator) in C++

You're mostly correct regarding cout and cin. ...READ MORE

Jun 27, 2022 in C++ by Damon
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440 views
0 votes
0 answers

How to use the priority queue STL for objects?

class Person { public: int age; }; I'd want to put objects of the type Person in a priority queue. priority_queue< ...READ MORE

Jun 27, 2022 in C++ by Nicholas
• 7,760 points
366 views
0 votes
1 answer

Why we actually need runtime polymorphism?

One of the most significant elements of ...READ MORE

Jun 10, 2022 in C++ by Damon
• 4,960 points
1,064 views