Trending questions in C++

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What does Tokens do and why they need to be created in C++ programming?

Tokenization is essential in determining what a programme does.  What Bjarne is referring to in respect to C++ code is how tokenization rules alter the meaning of a programme.  We need to know what the tokens are and how they are determined.  Specifically, how can we recognise a single token when it comes among other characters, and how should tokens be delimited if  there is ambiguity? Consider the prefix operators ++ and +, for example. Assume we have just one token + to deal with.  What does the following excerpt mean? int i = 1; ++i; Is the above going to apply unary + on i twice with + only? Or will it only increase it once? Naturally, it's vague.  We require an additional token, thus ++ is introduced as its own "word" in the language. But there is now another (though minor) issue.  What if the programmer just wants to use unary + twice without incrementing?  Rules for token processing are required.  So, if we discover that a white space is always used as a token separator, our programmer may write: int i ...READ MORE

Aug 2, 2022 in C++ by Damon
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Sorting a vector in descending order

Should I  utilize  std::sort(numbers.begin(), numbers.end(), std::greater<int>()); or std::sort(numbers.rbegin(), numbers.rend()); // ...READ MORE

Jul 5, 2022 in C++ by Nicholas
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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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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
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260 views
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How can I get double quotes into a string literal?

I used the printf() command to produce the output seen below: printf("She said time flies like an arrow, ...READ MORE

Aug 5, 2022 in C++ by Nicholas
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511 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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How do you open a file in C++?

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

Aug 8, 2022 in C++ by Nicholas
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355 views
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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
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220 views
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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
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464 views
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Confused with object arrays in C++

I have some Java knowledge and now ...READ MORE

Aug 11, 2022 in C++ by krishna
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188 views
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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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306 views
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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
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431 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
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287 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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504 views
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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
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374 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
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350 views
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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
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309 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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889 views
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1 answer

"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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303 views
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1 answer

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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281 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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756 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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583 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
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572 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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512 views
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1 answer

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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2,041 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
581 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
534 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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435 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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504 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
• 7,760 points
411 views
0 votes
0 answers

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
• 7,760 points
413 views
0 votes
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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
406 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
366 views
0 votes
1 answer

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
1,840 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
• 7,760 points
278 views
0 votes
0 answers

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
• 7,760 points
1,172 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
• 7,760 points
293 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
• 7,760 points
259 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
251 views
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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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301 views
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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
468 views
0 votes
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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
466 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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203 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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304 views
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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
• 7,760 points
219 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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378 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
• 7,760 points
244 views
0 votes
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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
227 views
0 votes
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Default inheritance access specifier

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

Jul 22, 2022 in C++ by Nicholas
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337 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
• 7,760 points
236 views