Trending questions in C++

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How come an array's address is equal to its value in C?

The pointer values and pointer addresses in ...READ MORE

Aug 8, 2022 in C++ by krishna
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752 views
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1 answer

Why would anyone use set instead of unordered_set?

Unordered sets must compensate for their O(1) ...READ MORE

Jun 1, 2022 in C++ by Damon
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3,670 views
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Conversion of base 10 to base 6

I attempted to convert a base 10 number to a base 6 number in C, but my code failed two hidden test cases. I don't see any logical flaws in it. Could you do it? //convert base 10 to base 6 #include<stdio.h> int main() { ...READ MORE

Jul 26, 2022 in C++ by Nicholas
• 7,760 points
1,230 views
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Which is better way to calculate nCr

Approach 1: C(n,r) = n!/(n-r)!r! Approach 2:  I discovered this in Wilf's book Combinatorial Algorithms: C(n,r) may be represented as C(n-1,r) + C (n-1,r-1). e.g. C(7,4) = C(6,4) + ...READ MORE

Jul 25, 2022 in C++ by Nicholas
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1,280 views
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How does sizeof know the size of the operand array?

It could be a silly question, but ...READ MORE

Aug 17, 2022 in C++ by Nicholas
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edited Mar 4 255 views
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Examples of good gotos in C or C++

Here's one method I've heard of folks use. But I've never seen it in the wild.  And that only pertains to C since RAII allows you to accomplish this more idiomatically in C++. void foo() { if (!doA()) ...READ MORE

Aug 2, 2022 in C++ by Damon
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838 views
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How do I set up Visual Studio Code to compile C++ code?

Although the Visual Studio Code editor from ...READ MORE

Aug 17, 2022 in C++ by Nicholas
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edited Mar 4 230 views
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"We do not use C++ exceptions" — What's the alternative? Let it crash?

If you don't utilise exceptions, by definition, ...READ MORE

Aug 2, 2022 in C++ by Damon
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823 views
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What is meant with "const" at end of function declaration?

I received a book in which it is written: class Foo { public: int ...READ MORE

Jul 28, 2022 in C++ by Nicholas
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954 views
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Storing C++ template function definitions in a .CPP file

I have some template code that I'd rather have saved in a CPP file rather than inline in the header.  I know this is possible if you know which template types will be utilised.  As an example: .h file class foo { public: template <typename ...READ MORE

Jul 26, 2022 in C++ by Nicholas
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1,080 views
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Adding to a vector of pair

I have a pair vector that looks like this: vector<pair<string,double>> revenue; I'd want to add a string and a double from a map that looks like this: revenue[i].first = "string"; revenue[i].second = map[i].second; However, because revenue is not initialised, it returns an out of bounds error.  So I ...READ MORE

Jul 26, 2022 in C++ by Nicholas
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1,079 views
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Check if a string contains a string in C++

I've got a std::string variable. I'd want ...READ MORE

Jul 28, 2022 in C++ by Nicholas
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967 views
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Simple dictionary in C++

Changing some Python code to C++. BASEPAIRS = { "T": "A", "A": "T", ...READ MORE

Jul 26, 2022 in C++ by Nicholas
• 7,760 points
975 views
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Understanding c++ Code: Tower of Hanoi using Recursion

I'm studying about recursion in C++, but the following C++ code used to solve the Tower of Hanoi issue has me baffled. void Hanoi(int m, string start, string middle, ...READ MORE

Jul 26, 2022 in C++ by Nicholas
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964 views
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const int *p vs. int const *p - Is const after the type acceptable?

My coworker is 0 for 2 on questions inspired by him (1, 2), so I decided to give him a chance to catch up. Our most recent argument is about the placement of "const" on declarations. He believes it should be placed either in front of the type or after the pointer.  The explanation is that this is what everyone else does, and different styles are likely to be confusing.  Thus, a constant pointer to int and a constant pointer to int would be: const int *i; ...READ MORE

Jul 22, 2022 in C++ by Nicholas
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1,050 views
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Accumulate function in Vector (STL) giving negative sum

I'm receiving a negative total when I run the code below (-294967296). #include<iostream> #include<vector> #include<numeric> using namespace std; int main() { ...READ MORE

Jul 22, 2022 in C++ by Nicholas
• 7,760 points
1,045 views
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How to code a modulo (%) operator in C/C++/Obj-C that handles negative numbers

As a mathematician, one of my pet peeves of C-derived languages is : (-1) % 8 // comes out as ...READ MORE

Jul 27, 2022 in C++ by Nicholas
• 7,760 points
803 views
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Is there a default return value of C++ functions?

I'm amazed that a file with the  ...READ MORE

Jul 25, 2022 in C++ by Nicholas
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949 views
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How to concatenate two strings in C++?

I have a private class variable char ...READ MORE

Jul 25, 2022 in C++ by Nicholas
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929 views
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Simple C++ swap function

Why is it that if I have a method like this to swap two numbers, it doesn't work[swap], (I know I can accomplish this by defining pointers in the prototype and then passing the addresses of the relevant variables in main()), yet it works for arrays without having to supply pointers and addresses? It does not work. void num_exchange(int m, int n); int main(){ int num1 ...READ MORE

Jul 27, 2022 in C++ by Nicholas
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746 views
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How to declare an array of strings in C++?

I am trying to iterate over all ...READ MORE

Jul 26, 2022 in C++ by Nicholas
• 7,760 points
918 views
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What type of members can I add in a c++ abstract class

Hello, let's say I have an abstract class with a few pure abstract functions and a few classes that derive from it, and all of the data from these classes eventually becomes similar, I was wondering if it would be wise, or even possible, to declare a vector under protected in the abstract class to collect the data so something like that. class A { protected: vector <string> ...READ MORE

Jul 27, 2022 in C++ by Nicholas
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727 views
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Container Class vs Class - C++

I'm new to programming and have only ...READ MORE

Jul 28, 2022 in C++ by Nicholas
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678 views
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Successor of INT_MAX and INT_MIN

I have two inquiries. Is 1e9 smaller than ...READ MORE

Jul 15, 2022 in C++ by Nicholas
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1,176 views
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Ternary operator, if I avoid writing ' expression 2 ' it works but if I not write 'expression 3 ' it gives an error [duplicate]

6.8 Conditionals with Missing Opponents In a ...READ MORE

Jun 28, 2022 in C++ by Damon
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2,041 views
0 votes
0 answers

Run C++ in command prompt - Windows

What may be the cause? I know ...READ MORE

Jul 22, 2022 in C++ by Nicholas
• 7,760 points
1,043 views
0 votes
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What is the difference between a concrete class and an abstract class?

I'm learning C++, but I'm having trouble ...READ MORE

Jul 26, 2022 in C++ by Nicholas
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807 views
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Difference between upper_bound and lower_bound in stl

I was looking at how the upper bound and lower bound algorithms operate in stl on these pages: lower bound, upper bound, and it's documented the same way on these pages: lower bound, upper bound, and it's documented the same way on these pages: lower bound, upper bound, and it'  upper bound, lower bound Looking at the code from the links, they appear to perform the same thing to me, with the exception of the following lines  lower_bound (line 10): if (*it<val) { ...READ MORE

Jul 5, 2022 in C++ by Nicholas
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1,639 views
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Default inheritance access specifier

If I have two classes A and ...READ MORE

Jul 22, 2022 in C++ by Nicholas
• 7,760 points
794 views
0 votes
1 answer

C++ code file extension? What is the difference between .cc and .cpp [closed]

GNU GCC recognizes all of the following ...READ MORE

Jun 21, 2022 in C++ by Damon
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2,248 views
0 votes
0 answers

What are the new features in C++17?

C++17 is currently feature complete, therefore major ...READ MORE

Jul 26, 2022 in C++ by Nicholas
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682 views
0 votes
1 answer

Sorting vector elements in descending order

Because of the goto reset instruction, I believe your sort function has entered an infinite loop.  If you wish to construct a basic bubble-sort algorithm, follow these steps: #include <iostream> #include <utility> #include <vector> void bubble_sort(std::vector<int>& v) { ...READ MORE

Jul 11, 2022 in C++ by Damon
• 4,960 points
1,427 views
+1 vote
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Using push_back vs at in a vector in C++

I'm not sure how to use vectors in C++.  It has to do with the vector's push back technique.  I used push back to insert entries into the vector in the first programme.  I used at() to insert entries into the vector in the second application. #include <iostream> #include <vector> #include <string> using namespace std; int main ...READ MORE

Jul 22, 2022 in C++ by Nicholas
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743 views
0 votes
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What is the fastest way to transpose a matrix in C++?

I have a reasonably large matrix that I need to transpose.  Assume, for example, that my matrix is a b c d e f g h ...READ MORE

Jul 15, 2022 in C++ by Nicholas
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1,017 views
0 votes
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What is the difference between ifstream, ofstream and fstream?

I stumbled discovered ifstream, ofstream, and fstream ...READ MORE

Jul 11, 2022 in C++ by Nicholas
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1,263 views
0 votes
0 answers

Why do we use volatile keyword?

I've never used it, but I'm curious ...READ MORE

Jul 25, 2022 in C++ by Nicholas
• 7,760 points
762 views
0 votes
1 answer

How do i apply lower_bound to a range of unsorted vector elements?

What's the point of sorting your array? ...READ MORE

Jun 15, 2022 in C++ by Damon
• 4,960 points
2,441 views
0 votes
0 answers

What are access specifiers? Should I inherit with private, protected or public?

I'm not sure what access modifiers signify ...READ MORE

Jul 22, 2022 in C++ by Nicholas
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731 views
0 votes
0 answers

How member functions are implemented in C++?

I read somewhere that member functions in C++ are similar to regular functions but with an additional implicit this parameter. As a result, I assumed that this software would be unable to discriminate between two functions.  However, the software executed successfully.  So, was the above statement incorrect? #include <iostream> class MyCls { ...READ MORE

Jul 22, 2022 in C++ by Nicholas
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728 views
0 votes
1 answer

How can I get all the unique keys in a multimap

This method worked for me. for( multimap<char,int>::iterator it ...READ MORE

Jun 27, 2022 in C++ by Damon
• 4,960 points
2,003 views
0 votes
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Converting Binary to Decimal built-in function

In C++, I need to do a ...READ MORE

Jul 15, 2022 in C++ by Nicholas
• 7,760 points
1,152 views
0 votes
0 answers

Using "super" in C++

The following phrase is part of my coding approach: class Derived : public Base { ...READ MORE

Jul 13, 2022 in C++ by Nicholas
• 7,760 points
1,166 views
0 votes
0 answers

Visual C++ vs Visual C# , which is the best to learn?

I completed my C++ lessons and practises ...READ MORE

Jul 22, 2022 in C++ by Nicholas
• 7,760 points
706 views
0 votes
0 answers

How to find if a given key exists in a C++ std::map

I'm trying to check if a given ...READ MORE

Jul 14, 2022 in C++ by Nicholas
• 7,760 points
1,100 views
0 votes
0 answers

XOR Operation Intuition

Except for one, every element in an array of numbers appears twice.  Locate that solitary one. Keep in mind that your algorithm should have a linear runtime complexity.  Could you do that without using any more memory? class Solution { public: int ...READ MORE

Jul 22, 2022 in C++ by Nicholas
• 7,760 points
670 views
0 votes
0 answers

Simple example of threading in C++

Could someone maybe provide a basic C++ ...READ MORE

Jul 15, 2022 in C++ by Nicholas
• 7,760 points
904 views
0 votes
1 answer

c++ constructor and copy constructor

In a pre-C++17 compiler, this is known as copy elision (test it with C++17 on compiler explorer or wandbox with -std=c++17 vs. -std=c++14 flags).  As of C++17, the compiler must delete numerous instances of copy and move constructors and create objects directly without the need of intermediary objects. Unlike A a { 10 }; the line A a ...READ MORE

Jun 27, 2022 in C++ by Damon
• 4,960 points
1,941 views
0 votes
1 answer

Why is Turbo C++ showing this error in DOSBox on my Mac?

Your installation must be defective!  I have a Mac, and I'm typing this on it while using TurboC++.  Consider uninstalling and then reinstalling the programme. Download the package in the same way as you would a.dmg programme from the internet.  (For example, drag and drop the programme into the Applications folder)  Ascertain that your Applications folder is global to your system.  This is what I mean: When in Finder, select the "GO" option from the top menu bar. From the drop down option, choose "Computer." In the newly opened window, click on your hard disc. There is a "Applications" folder there.  That's where you should put TurboC++. Go to Launchpad, and start Turbo C++. ...READ MORE

Jun 28, 2022 in C++ by Damon
• 4,960 points
1,743 views
0 votes
0 answers

When and why do I need to use cin.ignore() in C++?

In C++, I developed a simple application that requested the user to enter a number and then a string.  Surprisingly, when I ran the application, it never paused to ask for the string.  It simply ignored it.  After conducting some research on StackOverflow, I discovered that I needed to include the following line: cin.ignore(256, '\n'); before the line with the string input  That addressed the problem and allowed the software to run.  My issue is why C++ need the cin.ignore() line, and how can I forecast when I will need to use it. Here's the software I created: #include <iostream> #include <string> using namespace std; int main() { ...READ MORE

Jul 4, 2022 in C++ by Nicholas
• 7,760 points
1,263 views
0 votes
1 answer

What is the difference between public, private, and protected inheritance in C++?

To begin answering that question, let me characterise member accessors in my own terms.  If you already know this, proceed to the section "next:". I'm aware of three types of accessors: public, protected, and private. Let: class Base { public: ...READ MORE

Jul 11, 2022 in C++ by Damon
• 4,960 points
1,234 views