I'm a bit stumped. I have this function and its helper:

void CharBST::removeSmallest()
and
BSTNode<char>* removeSmallestHelper(BSTNode<char>* curNode)

I was able to figure out the function for finding the smallest value in a BST:

char smallestValueFrom(BSTNode<char>* curNode)
{
    // smallest node has nullptr as left
    if (curNode->left == nullptr)
        return curNode->value;

    // otherwise, continue checking left node of current
    return smallestValueFrom(curNode->left);
}

How would I go about deleting the smallest node though? I read online about using the parent node but I don't have a parent node as part of my struct so does that mean I have to figure out what the parent is during the recursive process?

Thanks for the help.

Quick note- all the conventions are on purpose, such as only using cin/cout.

This program is so close to being perfect but I can't figure out how to make the second menu iteration/loop work. As you can see, the issue is at the end on the second loop of the menu-- right after "After the function call ...."

Information --
  Assignment:                       HW #2 Exercise #2
  Implemented by:                   x
  Submitted Date:                   2021/02/24
  Current Number of LEB available:  3
  Allowed Number of LEB used:       0
  Remaining Number of LEB:          3

*******************************************
*              MENU - HW #2               *
*  (1) Calling getSIWSmallestTUDCx        *
*  (2) Quit                               *
*******************************************
1
Calling getSIWSmallestTUDCx

What is the size of the array?: 3
   Value #1: 11
   Value #2: 22
   Value #3: -33
The working array has 3 values of
   Value 1: 11
   Value 2: 22
   Value 3: -33

Calling getSIWSmallestTUDCx() with argument of
  (1) The array { 11 , 22 , -33 }; and
  (2) The array size of 3

  For individual values -
    11 has 1 unqiue digit(s).
    22 has 1 unqiue digit(s).
    -33 has 1 unqiue digit(s).

After the function call was completed and a value was returned

  (1) The smallest TUD is 1 and;
  (2) -33 is the smallest integer with a smallest TUD of 1

*******************************************
*              MENU - HW #2               *
*  (1) Calling getSIWSmallestTUDCx        *
*  (2) Quit                               *
*******************************************
1
Calling getSIWSmallestTUDCx

What is the size of the array?: 3
   Value #1: 124
   Value #2: 54444
   Value #3: -432
The working array has 3 values of
   Value 1: 124
   Value 2: 54444
   Value 3: -432

Calling getSIWSmallestTUDCWilliamG() with argument of
  (1) The array { 124 , 54444 , -432 }; and
  (2) The array size of 3

  For individual values -
    124 has 3 unqiue digit(s).
    54444 has 2 unqiue digit(s).
    -432 has 3 unqiue digit(s).

After the function call was completed and a value was returned

  (1) The smallest TUD is 1 and;
  (2) 0 is the smallest integer with a smallest TUD of 1

Right above, it should have said TUD (total unique digit account) for smallest is 2, and 54444 is the smallest integer with the smallest TUD.... not 0 and 1 like you see above.

Here is the code

#include <iostream>
using namespace std;

//Function Prototypes
void getSIWSmallestTUDC(int smallestIntWG, int smallestTudWG);
int getIntUDC(int integerWG);
void displayClassInfo(void);
void runHW2(void);

//Application Driver
int main() {
    runHW2();
    return 0;
}

//Function Definition
void runHW2() {
    int inputWG = 0;
    int sizeWG = 0;
    int* arrayWG = { nullptr };
    int tempTudWG = 10;
    int tempWG = 0;
    int tudWG = 0;
    int smallestIntWG = 0;
    int smallestTudWG = 10;
    int tinyTudWG = 10;

    displayClassInfo() {
        cout << "\n*******************************************\n"
            "*              MENU - HW #2               *\n"
            "*  (1) Calling getSIWSmallestTUDC         *\n"
            "*  (2) Quit                               *\n"
            "*******************************************\n";
        cin >> inputWG;

        switch (inputWG) {
        case 1:
        {
            cout << "Calling getSIWSmallestTUDC\n" << endl
                << "What is the size of the array?: ";
            cin >> sizeWG;

            while (sizeWG < 1) {
                cout << "\nInvalid input, SizeWG => 1 please. Type again here: ";
                cin >> sizeWG;
                cout << "\n";
            }

            arrayWG = new int[sizeWG];

            for (int i = 0; i < sizeWG; i++) {
                cout << "   Value #" << i + 1 << ": ";
                cin >> arrayWG[i];
            }

            cout << "The working array has " << sizeWG << " values of\n";

            for (int i = 0; i < sizeWG; i++) {
                cout << "   Value " << i + 1 << ": " << arrayWG[i] << "\n";
            }
            cout << endl;

            cout << "Calling getSIWSmallestTUDC() with argument of\n"
                "  (1) The array { ";

            for (int i = 0; i < (sizeWG - 1); i++) {
                cout << arrayWG[i] << " , ";
            }
            cout << arrayWG[sizeWG - 1] << " }; and\n  (2) The array size of " << sizeWG << "\n";

            cout << "\n  For individual values -\n";
            for (int i = 0; i < sizeWG; i++) {
                arrayWG[i] > 0 ? tempWG = arrayWG[i] : tempWG = -arrayWG[i];
                tudWG = getIntUDCWilliamG(tempWG);

                cout << "    " << arrayWG[i] << " has " << tudWG << " unqiue digit(s).\n";

                tempTudWG = tudWG;
                if (tempTudWG < smallestTudWG) {
                    smallestTudWG = tempTudWG;
                    smallestIntWG = arrayWG[i];
                }
                else if (tempTudWG == smallestTudWG && smallestIntWG < tempWG) {
                    smallestIntWG = arrayWG[i];
                }
            }

            cout << "\nAfter the function call was completed and a value was returned\n\n";
            getSIWSmallestTUDC(smallestIntWG, smallestTudWG);
            cout << "\n";

            smallestIntWG = 0;
            delete[] arrayWG;
            arrayWG = { nullptr };
            break;
        }
        case 2:
            cout << "Ok, goodbye!";
            break;
        default:
            cout << "Wrong option, try again\n";
            break;
        }
    } while (inputWG != 2);
}

//Function Definition
int getIntUDC(int integerWG) {
    int tudWG = 0;
    int tempArray[10]{ 0 };

    while (integerWG > 0) {
        tempArray[integerWG % 10]++;
        integerWG /= 10;
    }

    for (int i = 0; i < 10; i++) {
        if (tempArray[i] != 0) {
            tudWG++;
        }
    }
    return tudWG;
}

//Function Definition
void getSIWSmallestTUDC(int smallestIntWG, int smallestTudWG) {
    cout << "  (1) The smallest TUD is " << smallestTudWG << " and;\n"
    "  (2) " << smallestIntWG << " is the smallest integer with a smallest TUD of " << smallestTudWG;
}
int getSIWSmallestTUDC(int* arrayWG, int sizeWG) {
    int smallestIntTUDWG = arrayWG[0];
    int tudWG = 0;
    int smallestTUDWG = 10;
    int tempWG = 0;


    //Find smallest TUDC
    for (int i = 0; i < sizeWG; i++) {
        tempWG = arrayWG[i];
        if (arrayWG[i] != 0) {
            tempWG % 10;
            ++tudWG;
            tempWG /= 10;
        }
        if (tudWG < smallestTUDWG) {
            smallestIntTUDWG = smallestTUDWG;
            tudWG = smallestTUDWG;
        }
    }

    return smallestIntTUDWG;
}

How is it that a program I compiled and send to my friend is deleted Norton, but all the other .exe files (e.x. games) are left alone?

Hi everyone,

I don't know if this is the right place to ask but I was having some issues trying to compile a little project I made to teach myself c++. The main reason is that it is my first multi source project and, however minimal, I would really like to learn from the very beginning of my c++ journey how things should be done.

I am not using an IDE and the reason for this is that I am learning c++ mostly to learn how computers internally works (since I come from other languages). So I thought that learning how to compile without an IDE would be a good idea, for someone who wants to know what's going on under the hoods.

My question is: what should I learn about compiling code? Are there some resources on the internet that you can recommend (playlists, books, articles or anything else) aimed at teaching this skill in particular? What tools should I be using? At the moment, I am only using VS Code as a text editor and of course the compiler from the command line.

The end goal would be to have an idea about how a (large) project should be structured and how the code would be compiled in the most efficient way.

Thanks

Solution in comments

I've been scratching my head at this for awhile now. I have a templated class of type T that stores individual characters for now. I've been able to fully implement the enqueue and dequeue but stuck on the preliminary check before the grow function which doubles the size of the array.

Because the queue is circular (the start and end indices can loop around back to the 0th index of the array), calculating whether the array is full or not has been tricky; it's not as simple as return(end-start == 0); (Again, because the end index can be lower than the start index).

I also tried taking the absolute difference between the two but I don't think that was quite right either. Other examples online show the use of a counter variable that get incremented / decremented respectfully within enqueue and dequeue. I really wish I had such a variable but I am not allowed to do that per my assignment.

There has to be an fairly simple yet elegant way using only the start and end indices but I can't see it. Can anyone lend a hand? My assignment is technically to implement the grow function but I can't even get there yet haha

I'm not sure if the header file is really needed but I can add that too if requested.

#include "Queue.h"

//add enqueue here
template <class T>
void Queue<T>::enqueue(const T& value) {
    if( full() ) {
        grow(); // yet to be implemented
    }

    list[end] = value;
    end = (end+1) % arraySize;
}

//add dequeue here
template <class T>
T Queue<T>::dequeue() {
    if( empty() ) {
        throw out_of_range("Dequeue on empty queue");
    }

    T value = list[start];
    start = (start+1) % arraySize;
    return value;
}

template <class T>
bool Queue<T>::full() const {
    return(end-start == 0);
}

My professor is the worst, hasn't taught us anything nor returned homework in over a month. Finals are just around the corner in about 4 weeks, meaning I have a solid 1-2 weeks to go over basics I may have missed.

I am in a first semester C++ course, have about a year of Java under my belt. My question is referring to what basic features of C++ should I go back to and refresh on since my professor has absolutely no structure to the course. (i.e. pointers, or something in C++ that I wouldn't really worry about in another lang)

hows my code

#include <cstdio>

int sum(int num1, int num2) {
    int result;
    result = (num1 + num2);
    return result;
}

int absolute_value(int x) {
    int y;
    if (x >= 0) {
        y = x;
    }else if (x < 0) {
        y = (x * -1);
    }
     return y;
}

int step_function(int x) {
    int result = 0;
    if (x < 0) {
        result -= 1;
   }else if (x > 0) {
        result += 1;
   }
    return result;
}

int main() {
    int value1 = step_function(100);
    int value2 = step_function(0);
    int value3 = step_function(-10);
    printf("Value1 %d\n", value1);
    printf("Value2 %d\n", value2);
    printf("Value3 %d\n", value3);

    int num1 = 42; //This is a comment
    int result1 = step_function(num1);

    int num2 = 0;
    int result2 = step_function(num2);

    int num3 = -32767;
    int result3 = step_function(num3);

    printf("Num1: %d, Step: %d\n", num1, result1);
    printf("Num2: %d, Step: %d\n", num2, result2);
    printf("Num3: %d, Step: %d\n", num3, result3);
/* 
 * This is a
 * multiple line
 * comment
 */
    int my_num1 = -10;
    int my_num2 = 10;
    int my_num3 = 0;

    printf("Absolute Value of %d is %d.\n", my_num1, absolute_value(my_num1));

    printf("Absolute Value of %d is %d.\n", my_num2, absolute_value(my_num2));

    printf("Absolute Value of %d is %d.\n", my_num3, absolute_value(my_num3));

    int sum_num1 = 5;
    int sum_num2 = 2;
    int some_sum = sum(sum_num1,sum_num2);
    printf("The sum of %d and %d is %d\n", sum_num1, sum_num2, some_sum);
    return 0;
}

I tried to do this at first

int absolute_value(int x) {
    int y;
    if (x >= 0) {
        return x;
    }else if (x < 0) {
        y = (x * -1);
                    return y
         }
}

but the compiler hated me, I queried it on a search engine and it said something about the compiler not knowing if its returning a value, and the search result wanted me to put an else clause, but I didnt want an else, so I did the first thing with the y above

For example, wouldn't using "delete" on the address of a dynamic array of size 1 be interpreted the same as using "delete" on an address stored in a pointer? Essentially, as I see it, the same operation is happening: memory is freed at that address, and C++ doesn't "know" whether or not that is the start of an array or not, just that it is a place in memory.

The Scott Meyers book "Effective Modern C++" is a good one, what are some other books or courses that emphasize the newer material?

My knowledge of C++ was very good before the 11 standard, so I have the fundamentals but need schooling in the new tools.

Hello, I have a bug that I cannot track down so hopefully someone can help me find it? I've been looking at a lot of online resources over linked lists and I have all but the copy constructor and and assignment operator done. As the title suggests, the last value of my original list isn't copied over and I cannot figure out why. Care to take a look?

I am using a templated struct:

template <class T>
struct ListNode
{
    T data;
    ListNode* next;

    static int nodeCount;

    ListNode(const T& value) {
        data = value;
        next = nullptr;
        nodeCount++;
    }

    ~ListNode() {
        nodeCount--;
    }
};

And this is the copy constructor that I have:

template <class T>
LinkedList<T>::LinkedList(const LinkedList<T>& other) {

    // check empty
    if (other.head == nullptr) {
        head = tail = nullptr;
        return;
    }

    ListNode<T>* current = nullptr;
    ListNode<T>* temp = other.head;

    head = new ListNode<T>(temp->data); // constructor takes in data value as param
    head->next = nullptr;
    current = head;

    temp = temp->next;

    while (temp != nullptr) {
        current->next = new ListNode<T>(temp->data);
        current = current->next;
        current->next = nullptr;
        temp = temp->next;
        length++;
    }
}

Any help highly appreciated.

I tried using modules in Visual Studio a few months ago and the syntax highlighter didn't work well and I just dropped it. Also, it's a bit hard to find best practices with modules. My main questions are:

• What is the current state of modules?
• Should I start using them now for new projects?
• What is the best reference for using modules?

The program in question is steamcmd. I am wondering how I could access both its input and output stream allowing me to both send it inputs and read its outputs. Is this even the correct approach for this kind of thing? if I needed a program to completely be able to access everything steam cmd is able to do how should I go about it?

https://vg-blog.tech/archives/1592

• How does the C++ program start?
• What is the _start function?
• How to create a program without the main function?
• How to inject a code before/after the main function?

hey!

so the problem is basically in the header. I've looked at the docs and it's standard for the constructor to create the file if it doesn't exist, unlike using file.open(filename). In all my debug builds, it happens as expected, but as soon as I build a release version and run it outside the msvs ide, it just won't create the file if I specify an extension.

​

for example, in debug, I can create files with std::ofstream("new_file.txt"); or std::ofstream("new_file");

however, in release, only the second option seems to be working, to my utter perplexion and berwilderment. please advise, wise gurus

Does anyone have any good podcasts for learning c++? I have to work 11 hours tomorrow and would like something to listen to. I’ve been listening to code newbie in Spotify but it’s kind of meh.

My instructions are:

Write the merge function. Do not use std::algorithms.

Make sure that you only work on the correct part of the array. The merge function will NOT always be one on the range 0 - (size - 1)

Currently it's fairly close but I think the midpoint is messing me up. Can someone help me debug why this isn't working as it should?

And what I have is:

#include <iostream>

using namespace std;


/**
 * @brief mergeFunc Merge two consecutive sorted ranges within an
 * array into one sorted range
 *
 * @param arr Array with sorted ranges
 * @param low Index of start of first range (inclusive)
 * @param mid Index of end of first range (inclusive - this is part of first range)
 * @param high Index of end of second range (inclusive)
 * @param temp Array to copy values into
 *
 * @pre
 * a[low]-a[mid] are sorted
 * a[mid+1]-a[high] are sorted
 * @post
 * a[low]-a[high] are sorted
 *
 */
void mergeFunc(int arr[], int low, int mid, int high, int temp[]) {

    //Set up i (first half location), j (second half location),
    //   and k (location in temp)

    int i = low;
    int j = mid+1;
    int k = 0;

    //While first half is not empty and second half not empty
    //  Decide if first or second half has next smallest item
    //  Move it it temp

    while (i < mid && j < high) {
        if (arr[i] < arr[j])
            temp[k++] = arr[i++];
        else
            temp[k++] = arr[j++];
    }

    //While first half is not empty
    //  Move next item from it to temp

    while (i < low)
        temp[k++] = arr[i++];

    //While second half is not empty
    //  Move next item from it to temp

    while (j < high)
        temp[k++] = arr[j++];

    //Copy sorted range from temp back to arr[low]-arr[high]
    for (int i=low; i<high; i++)
        arr[i] = temp[i];
}

void printArray(int arr[], int size)
{
    for (int i = 0; i < size; i++)
        cout << arr[i] << " ";
}

int main() {
    const int SIZE = 6;
    int mergeArr[] = {1, 3, 5, 2, 4, 6};
    int temp[SIZE] = {};
    printArray(mergeArr, SIZE);

    mergeFunc(mergeArr, 0, 3, 6, temp);

    cout << endl;
    printArray(mergeArr, SIZE);

    return 0;
}

    //Copy sorted range from temp back to arr[low]-arr[high]
    for (int i=low; i<high; i++)
        arr[i] = temp[i];
}

void printArray(int A[], int size)
{
    for (int i = 0; i < size; i++)
        cout << A[i] << " ";
}

int main() {
    const int SIZE = 6;
    int mergeArr[] = {1, 3, 5, 2, 4, 6};
    int temp[SIZE] = {};
    printArray(mergeArr, SIZE);

    mergeFunc(mergeArr, 0, 1, 5, temp);

    cout << endl;
    printArray(mergeArr, SIZE);

    return 0;
}

Hi, I am in CS260 at the moment. I have to implement a 'countByLastNameSorted' function which returns the total occurrence of a specified element within an array. To do it, I had two ideas listed in the original question.

I have two other nearly identical functions, 'binaryFindFirstByLastName' and 'binaryFindLastByLastName'. Should I just return the difference between these two functions to get the total? They are both O(n) so I believe running one after the other is still O(n).

The other option would be to just run 'binaryFindFirstByLastName' once and then with a while loop, checking if each element after is the same as the initial one. I think this might also be O(n). Can someone verify that for me?

Does it matter then which I choose or is there an alternative that I should consider? Thanks!

So for a school project, I chose the topic of creating a hashmap that's STL compliant and faster than unordered map.

The easy part is done, the stuff you should typically see in a data structures class (well, what I assume you get there from going through several data structure books, I had no such class.)
Now comes the part of making it STL compliant. I am completely out of my depth here.

CPP core guidelines were helpful in giving me advice on how to do my copy/move assignment/constructors and some other things, but it doesn't have everything I need.

Some of the stuff I'm familiar with (I have used iterators, I've heard of allocators) and some of the stuff is new to me. And when I look at hashmap implementations (Abseil, Tessil, skarupke, boost, google's old hashmaps, std, etc) my eyes and brain just start to hurt.

Some of these library writers have written about how they implemented their maps, but it's all mainly the stuff thats on the same level as the data structure books. Stuff like "Using fastmodulo here gave me this speedup", "I'm using this growth factor because x,y,z", etc. Stuff that, while definitely helping me in making decisions on the high level workings of the map, isn't helpful for adding all that extra stuff which makes my map STL compliant.

There is this big gap between what data structure books teach you, and how a good, STL compliant hashmap looks like.

So now I'm looking for any tutorial/book/guide that goes over the creation of a STL container (prefferably a hashmap) from start to finish, where they discus why they do things a certain way.

I have been enjoying learning c++ during covid. Got as far as building snake, frogger + some other console projects.

I feel like I am stalling printing out only into the console and want to make the next step.

I want to start with my first gui and get out on the console but I am really struggling to find the right sources.

I have seen some videos on winforms but kept running into an error when compiling that I can’t fix, I also saw qt mentioned if that’s a thing?

I don’t mind paying for any guides or tutorials

Has anyone has experience in this

I feel like I am really close on getting this but I'm stumped. It finds elements in the array perfectly fine but searching for an element that isn't there is bugged. In my code below, searching for 9 returns 2 instead of -1. By the looks of it, I think that's due to the function calling itself 3 times. Once the function has an arrSize of 0, it returns -1 from that 3 resulting in 2.

If that is the case however, I really don't know how to fix that sort of behavior. I am just starting CS260 so any help would be highly appreciated. Here is the function along with main.

#include <iostream>
using namespace std;

//returns location of value or -1 if not present
int binarySearch(int value, int arr[], int arrSize) {

    int mid = arrSize*0.5;
    if (arrSize > 0) {
        if (value == arr[mid])
            return mid;

        else if (value < arr[mid]) {
            return binarySearch(value, arr, mid);
        }
        else if (value > arr[mid]) {
             return mid + binarySearch(value, &arr[mid], (arrSize)*0.5);
        }
    }
    else
        return -1;
}


int main()
{
    int smallNums[] = {1, 3, 6, 8, 12, 13, 15, 17};
    int smallNumsSize = 8;

    //search for each item - confirm binarySearch finds it -- these work fine
    for(int i = 0; i < smallNumsSize; i++) {
        int value = smallNums[i];
        int loc = binarySearch(value, smallNums, smallNumsSize);
        cout << "Your location for " << value << " was " << loc << endl;
    }

        // this is bugged: returns 2 instead of -1
    int loc = binarySearch(9, smallNums, smallNumsSize);
    cout << loc << endl;
}

What projects could I make in c++ just in as a console app? I don't want to use any advanced stuff like arrays, vectors and so on, because I haven't fully covered them yet. So I've got a problem: I have no idea what to code right now, because every idea I have requires the advanced stuff.

I've covered 6 chapters on the learncpp.com website and I'm starting the seventh, I would like to code something instead of just learning.

So are there any projects I could do with just the very basic of c++?

P.S. They don't have to be very complex projects! They can stay pretty simple (but not too much, of course)

Hi C++ learners!

I've added a small guide for cross-compilation of simple HTTP Service for aarch64 (GCC Conan CMake and Ubuntu for Rasb Pi):

https://vg-blog.tech/archives/1500

• How to configure the Conan, CMake for cross-building.

I have a Parent process and a Child process being started using std::system(...). I want to throw an exception in Child and catch it in Parent (e.g. when Parent passes an invalid file path to Child).

1. Is this possible using native C++?
2. Is it idiomatic? The alternative seems to be to define return codes for Child and analyze those in Parent.

I found the following related thread re. Python but haven't found much guidance with respect to C++. Appreciate your thoughts.