C ++堆栈模板SIGTRAP错误

Question

Just started learning about stack templates and ran into an issue while working on the push function whenever I try to free up memory to resize. The function works fine all the way up until it has reached maximum capacity, and then immediately goes into a series of error messages not really picked up by my debugger. Here's the header file with the function causing the error, plus the function it calls.

#include <iostream>
#include <string>
#include <sstream>
using namespace std;

template <class T>

class MyStack
{
  private:
  T* data;
  int topVal;
  int capacity;

  public:
  MyStack()
  {
    capacity = 10;
    topVal = 0;
    data = new T[capacity];
  }

  ~MyStack()
  {
    delete [] data;
    data = 0;
  }
  void push(T);
  T pop();
  T top();
  bool isFull();
  bool isEmpty();
  string toString();
};

template <class T>
void MyStack<T>::push(T value)
{
  if(!isFull())
  {
    data[++topVal] = value;
  }
  else
  {
    capacity *= 2;
    T* holdPtr = new T[capacity];
    for(int i = 0; i <= topVal; ++i)
      holdPtr[i] = data[i];
    delete [] data;                 //This is where the error is occurring
    data = holdPtr;
    data[++topVal] = value;
  }
}


template <class T>
bool MyStack<T>::isFull()
{
  if(topVal < capacity)
    return false;
  else
    return true;
}

Any help would be greatly appreciated.

EDIT: Problem solved! Thanks for all the help!

Answer 1

Two (related) problems:

1) With an empty stack, topval == 0 . But your push puts the element in data[++topVal] - ie, data[1] . data[0] is never used.

2) When topval == 9 and capacity == 10 , your isFull() returns false and your push tries to stores the value in data[10] , which is out-of-bounds and corrupts memory.

Also, your push should either take value by const reference or (if you are using C++11) use std::move .