Invalid use of non-static member function with header files - c++

Question

#define MYSQLPP_MYSQL_HEADERS_BURIED
#include <mysql++/mysql++.h>
#include <iostream>
#include "/home/sulli313/Project4/Film.h"
void Film::showList(){
std::cout << "\n-----------------------------------" << std::endl;
std::cout << " Query Application " << std::endl;
std::cout << "-----------------------------------" << std::endl;
std::cout << " 1 All letter name actors" << std::endl;
std::cout << " 2 First # PG-13 and Above" << std::endl;
std::cout << " 3 All active/inactive users by store" << std::endl;
std::cout << " 4 Actor Movie titles and ids" << std::endl;
std::cout << "-1 Exit" << std::endl;
std::cout << "-----------------------------------" << std::endl;
std::cout << ">> Enter your choice:" << std::endl;
}
void Film::showOne(){
mysqlpp::Connection myDB("cse278F2022", "localhost", "cse278F2022",
"raspberrySeltzer");
// Create a query
mysqlpp::Query query = myDB.query();
std::cout << "Please enter a Letter A-Z!" << std::endl;
std::string letter;
std::cin >> letter;
///////////////////////////////////Do this part/////////////////////////////////////////////
//if(letter)
query << "SELECT first_name, last_name "
<< "FROM actor "
<< "WHERE first_name "
<< "LIKE '" + letter + "%'";
// << "WHERE code = \"IST\"";
query.parse();
mysqlpp::StoreQueryResult result = query.store();
std::cout << "Here is your selection!\n" << std::endl;
std::cout << "--First/Last Names of Actors Whos First ";
std::cout << "Name Stars With " + letter + "--\n" << std::endl;
std::cout << std::left << std::setw(12) << "First Name" <<
std::setw(10) << "Last Name" << std::endl;
std::cout << "------------------------" << std::endl;
for (const auto & row : result) {
std::cout << std::left << std::setw(12) << row[0].c_str();
std::cout << std::setw(5) << row[1] << std::endl;
}
std::cout << "\n" << "to continue, press enter..." << std::endl;
showList();
}
void Film::showTwo(){
mysqlpp::Connection myDB("cse278F2022", "localhost", "cse278F2022",
"raspberrySeltzer");
//Selecting the second option's query
std::cout << "Please type a limit 1-30!" << std::endl;
std::string limit;
std::cin >> limit;
mysqlpp::Query query = myDB.query();
query << "SELECT title "
<< "FROM film "
<< "WHERE rating = 'PG-13' "
<< "OR rating = 'R' "
<< "OR rating = 'NC-17' "
<< "LIMIT " + limit + " ";
query.parse();
mysqlpp::StoreQueryResult result = query.store();
std::cout << "Here is your selection!\n" << std::endl;
std::cout << "--First "+ limit +" Titles PG-13 to NC-17--\n" << std::endl;
std::cout << std::left <<std::setw(20)<< "Title" << std::endl;
std::cout << "------------------------------" <<std::endl;
for (const auto & row : result) {
std::cout << std::left << std::setw(20) << row[0].c_str()<< std::endl;
}
std::cout << "\n" << "to continue, press enter..." << std::endl;
showList();
}
void Film::showThree(){
mysqlpp::Connection myDB("cse278F2022", "localhost", "cse278F2022",
"raspberrySeltzer");
//bind variable
std::cout << "Please type 1 for active and 0 for inactive!" << std::endl;
std::string active;
std::cin >> active;
if(active != "1" && active != "0"){
std::cout << "Wrong!" << std::endl;
std::cout << "Please type 1 for active and 0 for inactive!" << std::endl;
std::cin >> active;
}
//Selecting the second option's query
mysqlpp::Query query = myDB.query();
query << "SELECT Count(*) "
<< "FROM customer "
<< "WHERE active = '"+ active + "' "
<< "GROUP BY store_id";
query.parse();
mysqlpp::StoreQueryResult result = query.store();
std::cout << "Here is your selection!\n" << std::endl;
if(active == "1"){
std::cout << "--Count of All Active Users Grouped by Store Id--\n" << std::endl;
std::cout << std::left <<std::setw(20)<< "Active User Ids" << std::endl;
std::cout << "--------------------" <<std::endl;
} else {
std::cout << "--Count of All Inactive Users Grouped by Store Id--\n" << std::endl;
std::cout << std::left <<std::setw(20)<< "Inactive User Ids" << std::endl;
std::cout << "--------------------" <<std::endl;
}
for (const auto & row : result) {
std::cout << std::left << std::setw(20) << row[0].c_str()<< std::endl;
}
std::cout << "\n" << "to continue, press enter..." << std::endl;
showList();
}
void Film::showFour(){
mysqlpp::Connection myDB("cse278F2022", "localhost", "cse278F2022",
"raspberrySeltzer");
//bind variable
std::cout << "Please type an actor id that is 1-200!" << std::endl;
std::string act_id;
std::cin >> act_id;
//Selecting the second option's query
mysqlpp::Query query = myDB.query();
query << "SELECT film.title, film.film_id, film_actor.actor_id "
<< "FROM film, film_actor "
<< "WHERE film_actor.actor_id = "+ act_id +" "
<< "GROUP BY title "
<< "LIMIT 20";
query.parse();
mysqlpp::StoreQueryResult result = query.store();
std::cout << "Here is your selection!\n" << std::endl;
std::cout << "--First 20 Titles and IDs of Actor Id 25--\n" << std::endl;
std::cout << std::left <<std::setw(22)<< "Title" <<
std::setw(10)<< "Film_id" << std::setw(0)<<"Actor_id" << std::endl;
std::cout << "----------------------------------------" <<std::endl;
for (const auto & row : result) {
std::cout << std::left<<std::setw(22)<< row[0].c_str() << std::setw(10) << row[1] << std::setw(0) << row[2].c_str() << std::endl;
}
std::cout << "\n" << "to continue, press enter..." << std::endl;
showList();
}
#ifndef FILM_H
#define FILM_H
#include <iostream>
#include <string>
class Film {
public:
void showList();
void showOne();
void showTwo();
void showThree();
void showFour();
private:
};
#endif
// Copyright
// Purpose: Project 4
// Date 11/25/2022
// Author: Colton Sullivan
#define MYSQLPP_MYSQL_HEADERS_BURIED
#include <mysql++/mysql++.h>
#include <iostream>
#include "/home/sulli313/Project4/Film.h"
int main() {
int choice;
showList();
std::cin >> choice;
if (choice == -1) {
std::cout << "Bye!" << std::endl;
}
while (choice != -1) {
while ( choice > 4 || choice < -1 || choice == 0 ) {
std::cout << "The wrong choice!!!" << std::endl;
std::cout << "" << std::endl;
std::cout << "to continue, press enter...";
showList();
std::cin >> choice;
}
if ( choice == 1 ) {
showOne();
}
if ( choice == 2 ) {
showTwo;
}
if ( choice == 3 ) {
showThree;
}
if ( choice == 4 ) {
showFour;
}
std::cin >> choice;
if ( choice == -1 ) {
std::cout << "Bye!" << std::endl;
}
}
}
When trying to switch the original program to object oriented programming, I ran into the problem of the error "Invalid use of non-static member function" popping up for the showOne, showTwo, showThree, showFour and showList functions.
If there is a way to access the functions that are created in the Film.cpp/Film.h files and use them in the QueryApp.cpp file to run that as the main, please let me know.
I have tried switching it from Film::showOne, Film::showTwo...etc to showOne(); and Film::showOne(); but either the same Invalid use of non-static member function error will show or it will say that it has not be declared in this scope.

Answer 1

Your showSomething() functions are all member functions of the Film type. In particular, because they are not marked as static, they are non-static member functions. That means they operate on an instance of Film:
class C {
public:
void a(); // <- non-static member function
static void b(); // <- static member function
};
void foo() {
C::b(); // okay, doesn't need an object
C::a(); // not okay, needs an object
C object; // instance of C
object.a(); // okay
object.b(); // also okay
}
Typically you would give your object some state information or it raises the question why you have a non-static member function to begin with. If you don't need state, make them free functions (i.e., functions that are not member functions) or make them static.
In your case, I suppose it would be helpful to create a database connection in your Film's constructor so you can use the database member in all the functions that need a database connection to function.
Something like this:
class Film {
private:
mysqlpp::Connection myDB;
public:
Film() : myDB("x", "localhost", "y", "z") {}
// ...
};