创建了一个符合并使用整数运行的模板类,当我尝试使用字符串运行时,我收到无效的空指针错误。
我只添加了创建堆的方法,这是发现错误的地方。
//heap.h
#include <iostream>
#include <vector>
using namespace std;
template<class TYPE>
class Heap{
private:
vector<TYPE> heap;
int size;// number of elements in the heap
bool maxheap = true;//default value
TYPE bubble_up(TYPE item);
TYPE bubble_down(TYPE item);
public:
Heap();
Heap(bool maxheap);
Heap(vector<TYPE>, bool order);
~Heap();
void build_heap();
TYPE Insert(TYPE item);
TYPE Delete(TYPE& item);
const vector<TYPE> sort(bool order);
const vector<TYPE> sort();// defualt sort if no variable given, max sort
TYPE get_size();
void print_heap();
void clear_heap();
};
template<class TYPE>
Heap<TYPE>::Heap(){
TYPE dummy = 0;
heap.push_back(dummy);
size = heap.size() - 1;
}
template<class TYPE>
Heap<TYPE>::Heap(bool order){
maxheap = order; // true is max, false is min
TYPE dummy = 0;
heap.push_back(dummy);
size = heap.size() - 1;
}
template<class TYPE>
Heap<TYPE>::Heap(vector<TYPE> x, bool order){
maxheap = order;// true is max, false is min
TYPE tempSize;
TYPE dummy = 0;
heap.push_back(dummy);
size = heap.size() - 1;
tempSize = x.size();
for (TYPE y = 0; y < tempSize; y++){
heap.push_back(x[y]);
}
size = heap.size() - 1;
build_heap();
}
我已经删除了在接下来的几行代码中发现问题的部分。
//driver.cpp
#include <iostream>
#include <string>
#include "Heap.h"
using std::cout;
using std::endl;
typedef string TYPE;
int main(void) {
Heap<std::string> *s_heap = new Heap<std::string>(); // string heap
std::string s_item = "0";
}
“调试断言失败!” “表达式:无效的空指针”
答案 0 :(得分:2)
template<class TYPE>
Heap<TYPE>::Heap(){
TYPE dummy = 0;
heap.push_back(dummy);
size = heap.size() - 1;
}
第一行将转换为:
std:string dummy = 0;
我认为你不能将字符串设置为零。
尝试将其更改为:
TYPE dummy = TYPE();
更新: 正如juanchopanza指出的那样,现代语法是:
TYPE dummy{};
(我还活着过去......)