Trending questions in C++

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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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4,217 views
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How does "this" cascading work?

The following class interface I have is: ...READ MORE

Aug 16, 2022 in C++ by Nicholas
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1,674 views
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how could I use the power function in c/c++ without pow(), functions, or recursion

It is part of a series.  Replace pow() with the previous iteration's value. There is no need for code to call pow ().  Pow(x, 5 * I - 1) and pow(-1, I - 1) may be formed since both have an int exponent dependent on the iterator I from the previous loop iteration. Example: Let f(x, i) = pow(x, 5 * i ...READ MORE

Jun 21, 2022 in C++ by Damon
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4,181 views
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When to use extern in C++

This is useful when dealing with global variables.  Global variables are declared in a header so that any source file that contains the header is aware of them, but you only need to "define" them once in one of your source files. To explain, using extern int x; informs the compiler that an int object named x exists elsewhere.  It is not the compiler's responsibility to know where it exists; it just needs to know the type and name so that it may utilise it.  After compiling all of the source files, the linker will resolve all x references to the one definition found in one of the generated source files. For it to operate, the x variable's declaration must have "external linkage," which simply means that it must be defined outside of a function (at what's known as "the file scope") and without the static keyword. header: #ifndef HEADER_H #define HEADER_H // any source file that ...READ MORE

Jun 21, 2022 in C++ by Damon
• 4,960 points
4,073 views
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What is the difference between cout, cerr, clog of iostream header in c++? When to use which one?

I looked up the differences between cout, ...READ MORE

Jul 27, 2022 in C++ by Nicholas
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2,398 views
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Why was the ampersand chosen as the symbol for references in C++?

Does anyone know why the ampersand was ...READ MORE

Aug 16, 2022 in C++ by Nicholas
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1,491 views
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How to copy turbo c++ output?

How can I replicate the output of Turbo C++?  I had already Googled the issue, but in vain.  It suggests to either print scrn and paste or right click, select all, and paste.  I tried both, but neither worked.  The issue is that it simply copies what is on the current screen.  But I want the entire screen from the start.  (Alt+printscrn is also ineffective).  What should I do in this situation? printScrn Alt+printScrn markall None of them are operational!! I can't assist you if you require this archaic technique of programming for whatever reason, but I'd want to find a solution.  I tried forwarding the output stream to the file in this manner, but it did not work. #include<iostream.h> #include<conio.h> #include<stdlib.h> const int max=50; class dequeue{ int dq[max],r,f,c,x,i; public: dequeue(); void insertRear(); void insertFront(); void ...READ MORE

Jul 7, 2022 in C++ by Nicholas
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3,190 views
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How to generate a random number in C++?

I'm attempting to develop a dice game, and I need random numbers to represent the sides of the die.  I can make a number between 1 and 6).  Using #include <cstdlib> #include <ctime> #include <iostream> using namespace ...READ MORE

Aug 11, 2022 in C++ by Nicholas
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1,510 views
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How to use vector::push_back()` with a struct?

How do I push a struct back into a vector? struct point { int ...READ MORE

Jul 22, 2022 in C++ by Nicholas
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2,394 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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4,285 views
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how to print \" in C++

I need to print the following string: std::string("-I\"/path/to/dir\" "); Basically, I need to accomplish this since I am generating C++ code using C++ code. I want to use an ofstream to write the above string, so something like ofstream fout; fout << the_string ...READ MORE

Aug 11, 2022 in C++ by Nicholas
• 7,760 points
1,467 views
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Alternative function in iostream.h for getch() of conio.h?

I'm attempting to hold the screen on ...READ MORE

Aug 23, 2022 in C++ by Nicholas
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edited Mar 4, 2025 1,105 views
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How do you open a file in C++?

I want to open a file in ...READ MORE

Aug 8, 2022 in C++ by Nicholas
• 7,760 points
1,598 views
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How do you properly use namespaces in C++?

I come from a Java background where ...READ MORE

Aug 8, 2022 in C++ by Nicholas
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1,604 views
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1 answer

Why should I use reference variables at all?

References themselves are unrelated to the issue. The issue is because C++ manages object lifetimes differently from run-time systems that employ garbage collectors, such as Java.  There is no standard built-in garbage collector in C++.  Both automatic (within local or global scope) and manual (explicitly allocated/deallocated in heap) object lifetimes are possible in  C++. A C++ reference is nothing more than an object's alias.  It has no knowledge of object lifespan (for the sake of efficiency).  The coder must give it some thought.  A reference bound to a temporary object is an exception; in this situation, the temporary object's lifespan is prolonged to include the lifetime of the bound reference. References play a crucial role in the fundamental ideas of C++, and they are required for 90% of jobs.  Otherwise, pointers must be used, which is typically far worse. You can use references, for instance, when you need to give an object as a function parameter by reference rather than by value: void f(A copyOfObj); ...READ MORE

Aug 5, 2022 in C++ by Damon
• 4,960 points
1,806 views
0 votes
1 answer

Create a reverse LinkedList in C++ from a given LinkedList

A simpler solution is to just let the current node point to the previous node while going through your linked list, saving the previous and next nodes as you go. void LinkedList::reversedLinkedList() { if(head == ...READ MORE

Aug 5, 2022 in C++ by Damon
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1,780 views
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How to make an array with a dynamic size? General usage of dynamic arrays (maybe pointers too)?

I wanna create a program that can ...READ MORE

Aug 5, 2022 in C++ by krishna
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1,776 views
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C++ Switch Cases

I was taking an online quiz based on the C++ switch statement.  I came across a question, and while I have a good knowledge of how switch statements function, this particular question made no sense to me.  Could you please explain? Why is the answer D and not ...READ MORE

Jul 22, 2022 in C++ by Nicholas
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2,246 views
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How can I get the size of a C++ function?

In C++, how can I find the size& ...READ MORE

Aug 5, 2022 in C++ by Nicholas
• 7,760 points
1,572 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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3,692 views
0 votes
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Difference between 'struct' and 'typedef struct' in C++?

In C++, is there any difference between: struct Foo ...READ MORE

Aug 8, 2022 in C++ by Nicholas
• 7,760 points
1,629 views
0 votes
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What is a stream in C++?

I've been hearing a lot about streams, ...READ MORE

Aug 11, 2022 in C++ by Nicholas
• 7,760 points
1,279 views
0 votes
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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4,498 views
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memory allocation for objects

When we instantiate a variable in C++, ...READ MORE

Aug 11, 2022 in C++ by Nicholas
• 7,760 points
1,250 views
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What are Containers/Adapters? C++

What exactly are containers/adapters? I am familiar ...READ MORE

Aug 8, 2022 in C++ by Nicholas
• 7,760 points
1,447 views
0 votes
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What is the point of function pointers?

The purpose of function pointers is difficult ...READ MORE

Aug 17, 2022 in C++ by Nicholas
• 7,760 points
1,142 views
0 votes
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Insert object at index of vector c++

I have to add a new item to the existing object vector.  Although I am aware that an iterator must be used, I am not entirely sure how it operates. I need to insert a new item by name in the precise index that I found after some searching into an alphabetically sorted vector.  I have this, then. vector<Person>people; int index =54; Person temp; people.push_back(temp);//insert at end of ...READ MORE

Aug 5, 2022 in C++ by Nicholas
• 7,760 points
1,643 views
0 votes
0 answers

In C, are arrays pointers or used as pointers?

First, look at this code When this is ...READ MORE

Aug 11, 2022 in C++ by krishna
• 2,820 points
1,389 views
0 votes
0 answers

Alternative to itoa() for converting integer to string C++?

If I use itoa() to convert an ...READ MORE

Aug 23, 2022 in C++ by Nicholas
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edited Mar 4, 2025 833 views
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C++ - upcasting and downcasting

As an example: Shouldn't the second d.print() call during upcasting print "base"? Isn't it a "d" derived object that has been upcasted to a base class object? And what advantages does downcasting have? Could you describe upcast and downcast in more detail? #include <iostream> using namespace std; class Base { public: ...READ MORE

Jul 26, 2022 in C++ by Nicholas
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1,979 views
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How can i sort a map by its .second parameter

How can I output all the int ...READ MORE

Jul 28, 2022 in C++ by Nicholas
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1,821 views
0 votes
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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
• 7,760 points
1,973 views
0 votes
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Nested try...catch inside C++ exception handler?

I may wish to run code that might throw an exception in my exception handler. Is the following C++ structure acceptable?  Are there any drawbacks if so? try { // ... } catch (const ...READ MORE

Aug 5, 2022 in C++ by Nicholas
• 7,760 points
1,446 views
0 votes
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c++ custom compare function for std::sort()

I want to create custom compare function ...READ MORE

Aug 23, 2022 in C++ by Nicholas
• 7,760 points

edited Mar 4, 2025 789 views
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1 answer

Socket Programming in C++

The C++ Standard does not have a ...READ MORE

Aug 2, 2022 in C++ by Damon
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1,647 views
0 votes
1 answer

Reverse Contents in Array

My strategy would be as follows: #include <algorithm> #include <iterator> int main() { const int ...READ MORE

Aug 5, 2022 in C++ by Damon
• 4,960 points
1,560 views
0 votes
0 answers

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
• 7,760 points
1,746 views
0 votes
0 answers

Fast input/output in c++

In a programming question, I need to ...READ MORE

Aug 26, 2022 in C++ by Nicholas
• 7,760 points

edited Mar 4, 2025 585 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
• 7,760 points
1,959 views
0 votes
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Is it possible to get a single element of a set in C++ STL?

I have the following C++ code with ...READ MORE

Aug 26, 2022 in C++ by Nicholas
• 7,760 points

edited Mar 4, 2025 568 views
0 votes
0 answers

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
1,846 views
0 votes
0 answers

What is the difference between private and protected members of C++ classes?

What distinguishes C++ classes' private and protected ...READ MORE

Aug 26, 2022 in C++ by Nicholas
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edited Mar 4, 2025 563 views
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Rules for C++ string literals escape character

What are the string literals' escape character rules?  Are all the characters that are escaped listed somewhere? In particular, gedit colours the following three values differently when I use the symbol in a string literal. I was attempting to generate a std::string from a literal consisting of the character 0, the null character (0), and the character 0.  However, the syntax highlighting warned me that this would result in just two characters, such as the letter 0 followed by the null character (\00, aka \0). Is the following the best course of action for the solution to just this one issue: std::string ("0\0" "0", 3) // ...READ MORE

Aug 25, 2022 in C++ by Nicholas
• 7,760 points

edited Mar 4, 2025 604 views
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#defining constants in C++

In various C code, I see constants ...READ MORE

Aug 26, 2022 in C++ by Nicholas
• 7,760 points

edited Mar 4, 2025 543 views
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Is it more efficient to copy a vector by reserving and copying, or by creating and swapping?

I'm attempting to efficiently duplicate a vector. I see two potential strategies: std::vector<int> copyVecFast1(const std::vector<int>& original) { std::vector<int> newVec; ...READ MORE

Aug 23, 2022 in C++ by Nicholas
• 7,760 points

edited Mar 4, 2025 658 views
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When should you use 'friend' in C++?

I like the concept of the << ...READ MORE

Aug 25, 2022 in C++ by Nicholas
• 7,760 points

edited Mar 4, 2025 556 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
• 7,760 points
1,888 views
0 votes
0 answers

In C++, what is the difference between a method and a function

I'm making an effort to use the ...READ MORE

Aug 24, 2022 in C++ by Nicholas
• 7,760 points

edited Mar 4, 2025 575 views
0 votes
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
• 4,960 points
3,042 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
2,516 views