Learn note(cpp): take care when use new in a code block.

When I want to write a program to store the hash code of a file into a hash table, I find that whenever I expend the table and call the delete in the second time, an error: “double free” will occur.
HashNode* ht = new HashNode[len];
while(....){
if (overload(size)){
delete [] ht;
len = update(len);
HashNode* ht = new HashNode[len];
....
}
....
}
Just at the moment I call the delete at the second time, the error occurred.

Actually, it was my fault.
I’ve ignored the
type* var = new type;
is the same as
type* var;var = new type;
Yeah, this means I have to declare first, and then distribute the memory.
so the
HashNode* ht = new HashNode[len];
is not safe to use, because the ht I declared in “if ” will be released exactly after this block. Of cause the double free will occur.