Compact String Set with smart pointers - c++

Question

The project was to make our own set class that we went over, but to use smart pointers. I got all my functions to work without smart pointer, but now that I tried to use them I'm getting issues with creating a new node.
#include "cs19_compact_string_set.h"
#include <memory>
#include <queue>
#include <string>
#include <utility>
#include <vector>
#include <string>
namespace cs19 {
CompactStringSet::CompactStringSet() :root_{0}, num_strings_{0} {}
bool CompactStringSet::insert(const std::string& value) {
if (this->find(value)) return true;
auto cur = this->root_;
for (auto character : value) {
auto search = this->find_next(cur, character);
if (search) {
cur = search;
} else {
auto new_node = std::shared_ptr<CompactStringSet::Node>(character);
if (cur->child) {
cur = cur->child;
while (cur->sibling)
cur = cur->sibling;
cur->sibling = new_node;
} else {
cur->child = new_node;
}
cur = new_node;
}
}
if (!cur->terminal) {
++this->num_strings_;
cur->terminal = true;
}
return false;
}
std::shared_ptr<CompactStringSet::Node> CompactStringSet::find_next(const
std::shared_ptr<CompactStringSet::Node> base, char to_find) const {
if (base->child) {
if (base->child->letter == to_find)
return base->child;
auto sibling = base->child->sibling;
while (sibling) {
if (sibling->letter == to_find)
return sibling;
sibling = sibling->sibling;
}
}
return nullptr; // No match found
}
} // namespace cs19
In the file where the functions are being implemented I keep getting errors for trying to make a new shared_ptr with the value character. I've tried to change it in a few different ways. but can't solve the issue. The error keeps reading error: no matching function for call to ‘std::shared_ptrcs19::CompactStringSet::Node::shared_ptr(char&)’.
#ifndef CS19_COMPACT_STRING_SET_H_
#define CS19_COMPACT_STRING_SET_H_
#include <memory>
#include <queue>
#include <string>
#include <utility>
#include <vector>
#include <string>
namespace cs19 {
class CompactStringSet {
struct Node {
char letter; // each node stores a letter
bool terminal = false; // ... and is potentially the end of a string in the set
std::shared_ptr<Node> sibling = nullptr;
std::shared_ptr<Node> child = nullptr;
};
public:
CompactStringSet();
bool insert(const std::string& value);
bool find(const std::string& value) const;
bool end() const {
return false;
}
std::size_t size() const {
return this->num_strings_;
}
private:
std::shared_ptr<Node> root_{0};
std::size_t num_strings_ = 0;
std::shared_ptr<Node> find_next(const std::shared_ptr<Node> base, char to_find) const;};
} // namespace cs19
#endif

Answer 1

You are trying to create a new instance of CompactStringSet by giving it a character as a parameter in the constructor
auto new_node = std::shared_ptr<CompactStringSet::Node>(character);
But your structure doesn't take any parameters and doesn't have any constructor, it's what the error says.
So you should propably replace it by :
auto new_node = std::make_shared<CompactStringSet::Node>();
new_node->letter = character;
You should also use make_shared instead of shared_ptr when you want to create a new shared_ptr

Answer 2

You code fails because you are trying to invoke a non existent function here
auto new_node = std::shared_ptr<CompactStringSet::Node>(character);
Seems like you somehow expect this to create a new node, assign the character to its 'letter' member and create a shared_ptr pointing at the new node. This is wishful thinking, no such function exisits - hence
no matching function for call to ‘std::shared_ptrcs19::CompactStringSet::Node::shared_ptr(char&)’.
You need (since you have no constructor for 'node' that accepts a character argument)
auto new_nodew = std::make_shared<CompactStringSet::Node>();
new_node->letter = character;