no matching function for call to 'Journal::find_nom_journal()'

I want to insert information in a table in my db (view METHODE 1 insert_info())

In my code below I want to give the variable nom_journal the value same_path [nom_journal=same_path] that I returned in the second method (METHODE 2 (same_path).

I tried to give the variable nom_journal the name of the function cause it returned a string but it doesn't work. It gives me the following error

no matching function for call to 'Journal::find_nom_journal()'

*****METHODE 1 : *****

void Journal::insert_info()
{
    Db_response::ConnectionFunction();
    //Variables
    int id_journal= getId_journal();
    string nom_journal = find_nom_journal(); // --> THIS IS THE ERROR
    string s_id_journal(to_string(id_journal));

    string insert_query = "INSERT INTO `info_journal`(`id_journal`, `nom_journal`, `date`, `id_fournisseur`, `id_atm`, `state`, `state_parse_journal`, `terminal`, `id_utilisateur`) VALUES ('"+s_id_journal+"','"+nom_journal+"',' '  ,' ' ,' ' ,' ' ,' ' ,' ' ,' ' )";
    //int qstate = mysql_real_query(conn,insert_query.c_str(), strlen(insert_query.c_str()));
    query_state=mysql_query(conn, insert_query.c_str());
    if(!query_state)
    {

        cout << "Query Execution Problem " << mysql_errno(conn) << endl;
    }
    else
    {
         cout << endl << "success" << endl;
    }
}

METHODE 2**

string Journal::find_nom_journal(const char* path)
{
    string filename = string(path);
    ifstream file1(filename);
    string str_path = string(path);
    //find filename

    unsigned found = str_path.find_last_of("/\\");
    string same_path = str_path.substr(found+1);
    //cout << "this is the file name" << endl;
    cout <<same_path << endl;
    return same_path;

}