查找动态分配的数组的元素数

Question

I have a dynamically allocated array called Deck, composed of Card objects which have two values, suit and number.

I need to find the number of cards from my deck array, which I declared as so:

deck = new Card[52];

I'm not sure how to determine the amount of elements in the deck if I change the amount of cards in the deck array. Right now I have:

int size=0;
Card a;
while (a.getNumber() != '/0'){
    size++;
    a = deck[size];
}

where getNumber() is a function that pulls the number value of the card. However when I run the program is says "The program has stopped working"

Answer 1

This is not possible in C++, or C. You need to create a structure:

struct Deck { int nCards; Card *cards; }

or, better way is use std::vector<Card> , which already does that for you. If you really don't want a structure, and for some reason do not want to use a vector, allocate a dummy Card pointer and set it to null to mark the end of array:

deck = new Card[52+1];
deck[52] = 0;
while (deck[i]) { /* ... */ }

Answer 2

您可能必须将该数字与数组分开存储，执行类似C字符串的操作并使用sentinel值来指示数组的结尾，或者您实际上可以使用C ++编程并使用可以增长和缩小的向量。

Answer 3

I don't get what you mean when you say that the program says " The program has stopped working". I assume it's some sort of custom exception message.

However, I see a possibility of a buffer overflow (array index out of bounds exception) in your code.What if all the 52 slots in the array are occupied and then in the 52nd iteration,the value of the size variable turns 52 ,leading to an illegal index access in the deck array (it has been preallocated a set of 52 slots).

Also, this is certainly not a dynamically allocated array, because you are setting its size right at the initialization step.