Error in "Queue Management Part 1," C++ Intermediate

Question

I was trying to solve a Code Coach. The class was already created, the other methods were already there and stuff.

The prompt was to create an "add" method for the Queue class so that you can add an item to the end of a queue. Here's the whole code:
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#include <iostream>
using namespace std;

class Queue {
int size;
int* queue;
int increment;

public:
Queue() {
size = 0;
queue = new int[100];
}
void remove() {
if (size == 0) {
cout << "Queue is empty"<<endl;
return;
}
else {
for (int i = 0; i < size - 1; i++) {
queue[i] = queue[i + 1];
}
size--;
}
}
void print() {
if (size == 0) {
cout << "Queue is empty"<<endl;
return;
}
for (int i = 0; i < size; i++) {
cout<<queue[i]<<" <- ";
}
cout << endl;
}
//your code goes here
void add(int x) {
queue[increment] = x;
increment++;
size++;
}
};

int main() {
Queue q;
q.add(42); q.add(2); q.add(8); q.add(1);
q.print();
q.remove();
q.add(128);
q.print();
q.remove();
q.remove();
q.print();

return 0;
}
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And for some reason, it returns "timeout: the monitored command dumped core". It's one I haven't seen before, what's causing it?

Answer 1

you are using increment variable without initializing it first, then you are incrementing it which results in an Undefined Behavior.
just replace increment with size .

Answer 2

Yeah, it works perfectly now. Thanks!