Trending questions in C++

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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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277 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
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138 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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135 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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124 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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242 views
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1 answer

How do I use 'strlen()' on a C++ string

In C++, there are two standard methods for storing strings.  In this scenario, you specify an array of characters, and 0 signifies the end of the string. #include <cstring> char str[500] = "Hello"; // How ever ...READ MORE

Aug 2, 2022 in C++ by Damon
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339 views
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How to convert string to char array in C++?

Simplest way I can think of doing ...READ MORE

Jun 20, 2022 in C++ by Damon
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2,265 views
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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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295 views
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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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184 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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182 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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156 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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240 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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141 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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126 views
0 votes
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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113 views
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How to initialize an std::string with a length?

How can I correctly initialise a string if its length is specified at build time? #include <string> int length = 3; string word[length]; //invalid ...READ MORE

Jul 27, 2022 in C++ by Nicholas
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411 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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629 views
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0 answers

How can I terminate an infinite loop in Turbo C?

I get caught in an infinite loop.  How can I break this cycle?  Cntrl-C was attempted, however it had little effect.  I have no idea how to stop it. main() { ...READ MORE

Jul 13, 2022 in C++ by Nicholas
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937 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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318 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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306 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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210 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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303 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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161 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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416 views
0 votes
0 answers

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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188 views
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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
235 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
119 views
0 votes
0 answers

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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1,114 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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200 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
144 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
191 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
129 views
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0 answers

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
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126 views
0 votes
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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
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165 views
0 votes
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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
• 7,760 points
84 views
0 votes
0 answers

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
160 views
0 votes
0 answers

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
• 7,760 points
101 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
• 7,760 points
93 views
0 votes
0 answers

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
262 views
0 votes
0 answers

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
• 7,760 points
117 views
0 votes
0 answers

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
114 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
105 views
0 votes
0 answers

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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213 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
117 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
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148 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
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125 views
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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
116 views
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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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105 views
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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
101 views
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What is the difference between Java and C++?

What is the difference between Java and ...READ MORE

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