Question

Homework 2(11785,0x100082000) malloc: *** error for object     
enter code here0x73203a296b636f6c: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
d  c  b  a (lldb)

如果我在调试器中单步执行我的代码，则不会发生此错误，但不这样做，让我很难找到问题的根源。它也不会在每次运行程序时发生，但有时甚至在我根本不更改代码时也会发生。它也只在我在main中调用赋值运算符时开始出现，b = a。

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

typedef string ItemType;


class LinkedList {

private:
struct Node {
    ItemType value;
    Node *next;
};
Node *head;
int m_size;

public:

// default constructor
LinkedList() : head(nullptr) {
    m_size = 0;
}

// copy constructor
LinkedList(const LinkedList& rhs){
    head = nullptr;
    Node *p = nullptr;
    for (Node* n = rhs.head; n != nullptr; n = n->next)
    {
        Node* newNode = new Node;
        newNode->value = n->value;
        if (p != nullptr)
            p->next = newNode;
        if (head == nullptr)
            head = newNode;
        p = newNode;
    }
    m_size = rhs.m_size;
}

// Destroys all the dynamically allocated memory
// in the list.
~LinkedList(){
    Node* n = head;
    Node* prev = nullptr;
    while (n != nullptr) {
        prev = n;
        n = n->next;
        delete prev;
    }
}


// assignment operator
const LinkedList& operator=(const LinkedList& rhs){
    LinkedList *copy = new LinkedList (rhs);
    head = copy->head;
    m_size = copy->m_size;
    return *this;
}

// Inserts val at the front of the list
void insertToFront(const ItemType &val){
    Node* currentHead = head;
    head = new Node;
    head->value = val;
    head->next = currentHead;
    m_size++;
}

// Prints the LinkedList
void printList() const{
    Node* n = head;
    while (n != nullptr)
    {
        cout << n->value;
        n = n->next;
    }
}

int main(){
LinkedList a;
a.insertToFront(" a ");
a.insertToFront(" b ");
a.insertToFront(" c ");
a.insertToFront(" d ");
a.printList();
LinkedList b;
b = a;
return 0;
}

Answer 1

该错误实际上是在告诉您pointer being freed was not allocated。在C ++中释放指针意味着您在指针上使用delete运算符。这应该可以帮助你，而不会给你答案。

自己尝试并解决这些问题，特别是当它是家庭作业时。如果有人为您解决问题，您将无法学习。

通过smart pointers考虑自动内存管理。

祝你好运。

运行时malloc：***有时只出现错误

1 个答案: