C++ Trie中的浮点异常

Question

Trie实现的以下代码在调用函数insert时抛出浮点异常.for循环内部的行检查现有节点是问题所在.

struct Node {
    char c;
    bool isend;
    unordered_map<int, struct Node*> map;
};

void insert(struct Node* root, string contact) {
    int size = contact.size();
    char ch;

    for (int i = 0; i < size; i++) {
        ch = contact[i];
        // this check is creating problem
        if (root->map.find(ch) == root->map.end()) {
            struct Node* tmp = (struct Node*) malloc(sizeof(struct Node));
            tmp->c = ch;

            if (i == (size - 1)) {
                tmp->isend = true;
            } else {
                tmp->isend = false;
            }

            root->map.insert(make_pair(ch, tmp));
            root = tmp;            
       } else {
          root = root->map[ch];   
        }         

    }
}

int main()
{
    struct Node* root = NULL;

    root = (struct Node*) malloc(sizeof(struct Node));

    insert(root, "text");
}

有帮助吗？

Answer 1

不要在C++代码中使用malloc(除非你真的知道你在做什么)

root = new Node;

和

tmp = new Node;

问题是,因为你使用malloc,构造函数Node::map不会被调用.使用new将确保调用所有必需的构造函数.