To obtain the size of a C++ one-dimensional array after transferring it to a factor (primary)

Hello, I'm a C++ beginner.

You want to create a function that sends a one-dimensional array as a factor and obtains size, item, and a print function to output.

I made it as far as I know, but it's blocked afterwards.

Here's the question.

class Set {
private:
    int *set;
    int size = 0;
public:
    Set(int *set, int size);
    int getsize();
    int getitem(int index);
    void print();
};

Set::Set(int *set, int size) { 
    int item = 0;
    for (int i = 0; i < size; i++) {
        item = set[i];
    }
    int item size = sizeof(item) / sizeof(int); // why 1 is output..?
}

int Set::getsize() {
//return itemSize?
}

int Set::getitem(int index) {
}

void Set::print() {
}


void main() {
    int a[] = { 3,1,9,10,5,8 };
    int b[] = { 2,4,5,8 };
    Set a1(a, 6);
    Set a2(b, 4);
}

c++

2022-09-21 16:05

1 Answers

Hello! I will reply to you again this time... h;

I'll comment on the code and explain it to you.

class Set {
private:
    int *set;
    //intsize; Unnecessary variable. This is because a variable called item size was created.
    int itemsize;

public:
    Set(int *set, int _size);
    ~Set();
    int getsize();
    int getitem(int index);
    void print();
};

Please use Set::Set(int *_set /*) with the same name. */, int_size : itemsize(0)// Initialize member variable.
{ 
    // int item = 0; I think you used it to store an int-
    //               But you actually declared an int-type variable. And
    //               Since the constructor is also a function, the local variable declared inside the function is that the function is
    //               It disappears together at the end.
    this->set = new int[_size]{0,};

    for (int i = 0; i < _size; i++) {
        //item = set[i]; stored in the int-type variable will overwrite it again, so only the last data will be saved.
        this->set[i] = _set[i];
    }
    //itemsize = sizeof(item) /sizeof(int); // Why is 1 output..?
    // int item is a 4-byte int type variable. So if you divide by the size of int, you get 1.

    item size = _size; // We'll take over the size anyway, so you can use it as it is.

}

int Set::getsize() {
    Return item size; // You can use it as it is.
}

int Set::getitem(int index) {
    return this->set[index];
}

void Set::print() {
}

Set::~Set() {
    delete this->set;
}

int main() {
    int a[] = { 3,1,9,10,5,8 };
    int b[] = { 2,4,5,8 };
    Set a1(a, 6);
    Set a2(b, 4);

    return 0;
}

2022-09-21 16:05

If you have any answers or tips

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