Trending questions in C++

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what is containership or nesting in C++?

According to what I believed, a class ...READ MORE

Jul 11, 2022 in C++ by Nicholas
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1,225 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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1,509 views
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throwing a run time error

I just started Programming: Principles and Practice Using C++ because I'm new to programming.  Errors and how to handle them are covered in one of the chapters. What I'm attempting to implement is this little line of code.  The programme will end with a system error message and the text we gave as a parameter, according to the book's description of error(). #include <iostream> #include <string> using namespace std; int area (int ...READ MORE

Jul 13, 2022 in C++ by Nicholas
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1,177 views
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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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1,411 views
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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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1,334 views
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How to use std::sort to sort an array in C++

We receive std::begin and std::end in C++0x/11, which are overloaded for arrays: #include <algorithm> int main(){ int v[2000]; ...READ MORE

Jun 1, 2022 in C++ by Damon
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Purpose of Unions in C and C++

I had previously used unions with ease, but when I read this post and learned that this code union ARGB { uint32_t colour; ...READ MORE

Jul 13, 2022 in C++ by Nicholas
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1,132 views
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How does virtual inheritance solve the "diamond" (multiple inheritance) ambiguity?

You desire: (Achievable with virtual inheritance) ...READ MORE

Jun 10, 2022 in C++ by Damon
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2,601 views
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How to create a dynamic array of integers

How can I use the new keyword ...READ MORE

Jul 15, 2022 in C++ by Nicholas
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1,092 views
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Purpose of Unions in C and C++

I had previously utilised unions with ease; however, I was startled when I read this post and discovered that this code union ARGB { uint32_t colour; ...READ MORE

Jul 13, 2022 in C++ by Nicholas
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1,094 views
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What's the Use of '\r' escape sequence?

I have C code like this: #include<stdio.h> int main() { ...READ MORE

Jul 13, 2022 in C++ by Nicholas
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1,100 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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1,479 views
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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
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1,665 views
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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 2,372 views
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Sorting a vector of custom objects

A simple example using std::sort struct MyStruct { ...READ MORE

Jun 1, 2022 in C++ by Damon
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2,916 views
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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
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2,288 views
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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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1,858 views
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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
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1,740 views
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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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1,280 views
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Why we actually need runtime polymorphism?

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

Jun 10, 2022 in C++ by Damon
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2,470 views
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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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1,670 views
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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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1,709 views
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What is the best way to use a HashMap in C++?

The ordered and unordered map containers (std::map and std::unordered map) are included in the standard library.  The items in an ordered map are sorted by key, and insert and access are in O (log n).  For ordered maps, the standard library often use red black trees.  However, this is only an implementation detail.  Insert and access are in O in an unordered map (1).  It is simply another term for a hashtable. An illustration using (ordered) std::map: #include <map> #include <iostream> #include <cassert> int main(int argc, char ...READ MORE

Jun 10, 2022 in C++ by Damon
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2,454 views
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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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1,935 views
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Why use #define instead of a variable

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

Jul 1, 2022 in C++ by Nicholas
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1,216 views
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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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1,208 views
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outputting ascii table in C++

This line doesn't do the right thing: ch ...READ MORE

Jun 13, 2022 in C++ by Damon
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2,263 views
0 votes
1 answer

Error "Microsoft Visual C++ 14.0 is required (Unable to find vcvarsall.bat)"

For pip, use the binary-only option.  ...READ MORE

Jun 14, 2022 in C++ by Damon
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2,216 views
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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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1,646 views
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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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1,316 views
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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
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1,677 views
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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
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1,595 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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1,494 views
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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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1,693 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
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1,571 views
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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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1,453 views
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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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1,363 views
0 votes
1 answer

How to pass in command line arguments when using ideone?

It appears that you won't be able ...READ MORE

Jun 21, 2022 in C++ by Damon
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2,050 views
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1 answer

static memory allocation like dynamic memory allocation

This declaration int r, c; cin >> r >> ...READ MORE

Jun 7, 2022 in C++ by Damon
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2,403 views
0 votes
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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
1,399 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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1,505 views
0 votes
1 answer

abstract class and virtual functions

Is this class considered abstract because it only contains one virtual function?  I could still build an Animal object and use getFoodCost(); No. In C++, a "Abstract Class" is often a class having a single pure virtual function: class Abstract { public: virtual ...READ MORE

Jun 20, 2022 in C++ by Damon
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1,795 views
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Why are exceptions so rarely used in C++

I've been writing in C++ on and ...READ MORE

Jun 29, 2022 in C++ by Damon
• 4,960 points
1,263 views
0 votes
1 answer

implementing merge sort in C++

To respond to the question:  std::vectorT> is used to create dynamically sized arrays at runtime.  Ideally, you'd use one of these to get feedback.  If not, they are simple to convert.  For instance, you might make two arrays like this: template <typename T> void merge_sort(std::vector<T>& array) { ...READ MORE

Jun 10, 2022 in C++ by Damon
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2,103 views
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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
• 7,760 points
1,383 views
0 votes
1 answer

What is compile-time polymorphism and why does it only apply to functions?

"Compile time polymorphism" used to signify function overloading.  It only applies to functions because that's all you can overload. Templates in modern C++ modify this.  One example has previously been provided by Neil Butterworth.  Another technique is template specialisation.  As an example: #include <iostream> #include <string> template <class T> struct my_template { ...READ MORE

Jun 20, 2022 in C++ by Damon
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1,730 views
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How to use new[ ] and delete[ ] operator in C++

int main(){ char *str; ...READ MORE

Jun 20, 2022 in C++ by Damon
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1,726 views
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What is the STL?

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

Jun 29, 2022 in C++ by Damon
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1,175 views
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1 answer

C++ multiset, return key at position?

A set (or multiset) is typically represented ...READ MORE

Jun 27, 2022 in C++ by Damon
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1,292 views
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C++ pointer to objects

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

Jun 27, 2022 in C++ by Nicholas
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1,290 views