Question

I suppose I could just use a list however, at this point I am just curious why the following code does not work:

struct treeNode{  
    char symbol;  
    double freq;  
    int left;  
    int right;  
};

treeNode *tree;
int nOS = 16;
tree = (treeNode *)malloc(sizeof(treeNode) * nOS);
list<treeNode> treeList;

After initializing all the elements in tree I try to push them to treeList and get a segmentation fault, it does not occur if tree is treeNode tree[nOS] but I am working with an unknown number of elements so I need to be able to use realloc, hence the use of malloc:

for (int i = 0; i < nOS; i++) {
    treeList.push_back(tree[i]);
}

I tried casting tree[i] to a various number of things: (treeNode), (const treeNode) but I can’t figure out how to get it to work. Thank you!

Answer 1

I have done this in ideone, and it seems to work: (no segfaults)

#include<list>
#include<vector>
#include <stdlib.h>
#include<iostream>

struct treeNode{  
    char symbol;  
    double freq;  
    int left;  
    int right;  
};

int main(int argc, char** argv)
{
treeNode *tree;
int nOS = 16;
tree = (treeNode *)malloc(sizeof(treeNode) * nOS);
std::list<treeNode> treeList;

std::vector<treeNode> symbolList;

for (int i = 0; i < nOS; i++) {
    symbolList.push_back(tree[i]);
}

std::cout << symbolList.size();

};