用c ++映射初始化以实现尝试

Question

我试图在c ++中实现尝试.这是我使用的结构:

typedef struct tries{
    int wordCount;
    int prefixCount;
    map<int,struct tries*> children;
}tries;

该初始化方法:

void initialise(tries *vertex)
{
    vertex = (tries*)malloc(sizeof(tries*));
    vertex->wordCount = vertex->prefixCount = 0;
    for(char ch='a';ch<='z';ch++)
        vertex->children[ch]=NULL;

}

初始化方法具有分段故障在vertex->children[ch]=NULL;该故障是:

Program received signal SIGSEGV, Segmentation fault.
0x000000000040139a in std::less<int>::operator() (this=0x604018, 
    __x=@0x21001: <error reading variable>, __y=@0x7fffffffddb8: 97)
    at /usr/include/c++/4.6/bits/stl_function.h:236
236           { return __x < __y; }

怎么了？

Answer 1

malloc()如果您正在使用C++,则不应使用.此外,sizeof(tries*)如果需要创建大小为a的对象,则不应分配足够的内存来保存指针()tries.

使用new运营商:

vertex = new tries();

或者甚至更好,根本不使用new并避免使用原始指针进行手动内存管理new,并delete.考虑使用智能指针.

此外,在C++类中有构造函数,因此该initialise()方法实际上可以替换为构造函数tries:

struct tries
{
    tries() : wordCount(0), prefixCount(0) 
    {
        // ...
    }

    int wordCount;
    int prefixCount;
    map<int, struct tries*> children;
};