converting std::string to const char * and function calls

I have multiple methods inside my class which need const char * so I convert string to const char * inside the constructor of my class and store it in a local variable with type const char *. The local variable is valid inside the constructor. However, it is empty when I call it on methods of the same class.

If I pass it using const references my problem is fixed but I expected my code works without using const references.

I followed How to convert a std::string to const char* or char*? for other methods to convert the string to const char *.I think the c_str() convert the string correctly.

I want to understand the root cause which cause my local variable to be empty. I prepared example codes for my problem.

Code with problem: #include #include

using namespace std;

class Config{
string strFileName_ = "/path/filename.ext";
public:
    string getFileName() {return strFileName_;}
};


class Loader{
const char * className_;
public:
    Loader(string name){
        //className_ = name.c_str();   //same result with .data()
        className_ = name.data();
        cout << "[inside Loader constructor]className_ is:" << className_ << endl;
    }

    void loadFile(){
        cout << "[inside loadFile] className_ is:" << className_ << endl;
    }
};

int main(){
    Config cfg;
    Loader ld(cfg.getFileName());
    ld.loadFile();
}

Code with string instead of const char * does not have this problem. As I explained, if I use const references, the problem is not there anymore. Code for references: #include #include

using namespace std;

class Config{
string strFileName_ = "/path/filename.ext";
public:
    const string &getFileName() {return strFileName_;}
};


class Loader{
const char * className_;
public:
    Loader(const string& name) {
        className_ = name.c_str();
        cout << "[inside Loader constructor]className_ is:" << className_ << endl;
    }

    void loadFile(){
        cout << "[inside loadFile] className_ is:" << className_ << endl;
    }
};

int main(){
    Config cfg;
    Loader ld(cfg.getFileName());
    ld.loadFile();
}