DBapp logic
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873929cd83
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CT1/database
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#include <sqlite3.h>
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#include <iostream>
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#include <limits>
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#define RESET "\033[0m"
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#define RED "❌ \033[31m"
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#define GREEN "✅ \033[32m"
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#define BOLDWHITE "\033[1m\033[37m"
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constexpr const char* DB_FILE = "users.db";
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constexpr const char* MENU_MSG = "=== Database Management System ===\n1. Connect to database\n2. Execute custom SQL query\n3. Execute prepared SQL query\n4. Setup demo database\n5. Exit\n";
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constexpr const char* MENU_PREP_MSG = "=== Prepared Statement Menu: Select statement type ===\n1. SELECT\n2. INSERT\n3. EXIT\n";
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constexpr const char* MENU_PREP_COL_MSG = "=== Prepared Statement Menu: Select filter culumn ===\n1. Connect to database\n2. Execute custom SQL query\n3. Execute prepared SQL query\n4. Setup demo database\n5. Exit\n";
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constexpr const char* MENU_PREP_TYPE_MSG = "=== Prepared Statement Menu: Select filter type ===\n1. Connect to database\n2. Execute custom SQL query\n3. Execute prepared SQL query\n4. Setup demo database\n5. Exit\n";
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constexpr const char* DEMO_CREATE_TABLE = "CREATE TABLE IF NOT EXISTS users (ID INTEGER PRIMARY KEY AUTOINCREMENT, FirstName varchar(255) NOT NULL, LastName varchar(255) NOT NULL, Age int);";
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constexpr const char* DEMO_INSERT1 = "INSERT INTO users (FirstName, LastName, Age) VALUES ('Tedd', 'Chadwick', 23)";
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constexpr const char* DEMO_INSERT2 = "INSERT INTO users (FirstName, LastName, Age) VALUES ('Kathe', 'Claris', 31)";
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constexpr const char* DEMO_INSERT3 = "INSERT INTO users (FirstName, LastName, Age) VALUES ('Meryl', 'Chadwick', NULL)";
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constexpr const char* DEMO_SELECT1 = "SELECT * FROM users;";
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constexpr const char* DEMO_SELECT2 = "SELECT * FROM users WHERE LastName is 'Chadwick';";
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class DatabaseException : public std::exception {
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public:
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explicit DatabaseException() = default;
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DatabaseException(const char *errMsg) : errMsg(errMsg) {}
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const char* what() const noexcept override {
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return "Internal exception!";
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}
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private:
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const char *errMsg;
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};
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class InvalidArgument : public DatabaseException {
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const char* what() const noexcept override {
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return "Invalid argument!";
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}
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};
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class SQLiteException : public DatabaseException {
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public:
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SQLiteException(char *errMsg) : DatabaseException(), errMsg(errMsg) {}
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const char* what() const noexcept override {
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return errMsg;
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}
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~SQLiteException() {
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sqlite3_free((void*)(errMsg));
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}
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private:
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char *errMsg;
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};
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enum class MenuState {
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MENU,
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CONNECT = 1,
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QUERY_CUSTOM = 2,
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QUERY_PREPARED = 3,
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SETUP_DEMO = 4,
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EXIT = 5,
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};
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enum class StatementMenuState {
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MENU,
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SELECT = 1,
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INSERT = 2,
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EXIT = 3,
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};
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enum class ColumnMenuState {
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MENU,
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FIRST_NAME = 1,
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SECOND_NAME = 2,
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AGE = 3,
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EXIT = 4,
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};
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enum class FilterMenuState {
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MENU,
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IS = 1,
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IS_NOT = 2,
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LESS = 3,
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GREATER = 4,
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EXIT = 5,
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};
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std::istream& operator>>(std::istream& is, MenuState& state) {
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int a;
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if (!(is >> a)) {
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is.clear();
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is.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
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throw InvalidArgument();
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}
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state = static_cast<MenuState>(a);
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return is;
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}
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bool dbConnect(sqlite3** db, std::ostream& os) {
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int rc;
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os << "Connecting to SQLite...";
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if (*db) {
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constexpr const char* errMsg = "Already connected!";
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throw DatabaseException(errMsg);
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}
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rc = sqlite3_open(DB_FILE, db);
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if (rc != SQLITE_OK) {
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constexpr const char* errMsg = "Connecting failed!";
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throw DatabaseException(errMsg);
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}
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os << GREEN << "Connected\n" << RESET;
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return true;
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}
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int printQuery(void *os_vp, int argc, char **argv, char **colName) {
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std::ostream& os = *static_cast<std::ostream*>(os_vp); // oh god...
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for (int i = 0; i < argc; i++) {
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os << colName[i] << " = " << (argv[i] ? argv[i] : "NULL") << '\n';
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}
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os << '\n';
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return 0;
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}
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bool sendQuery(sqlite3* db, std::ostream& os, const char* q, int (*callback)(void *, int, char **, char **)) {
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int rc;
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char* errMsg;
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void* os_p = &os; // oh god...
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os << "Sending query: '" << q << "'...";
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rc = sqlite3_exec(db, q, callback, os_p, &errMsg);
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if (rc != SQLITE_OK) {
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throw SQLiteException(errMsg);
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}
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os << GREEN << "Successful\n" << RESET;
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return true;
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}
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bool setupDemo(sqlite3** db, std::ostream& os) {
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dbConnect(db, os);
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os << "Creating table 'users':\n";
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sendQuery(*db, os, DEMO_CREATE_TABLE, nullptr);
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os << "Adding records:\n";
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sendQuery(*db, os, DEMO_INSERT1, nullptr);
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sendQuery(*db, os, DEMO_INSERT2, nullptr);
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sendQuery(*db, os, DEMO_INSERT3, nullptr);
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os << "Testing queries:\n";
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sendQuery(*db, os, DEMO_SELECT1, printQuery);
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sendQuery(*db, os, DEMO_SELECT2, printQuery);
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return true;
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}
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bool preparedStatementMenu(sqlite3* db, std::ostream& os, std::istream& is) {
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return true;
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}
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bool executePrepared(sqlite3* db, std::ostream& os) {
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}
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int main(int ragc, char* argv[]) {
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std::ostream& os = std::cout;
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std::istream& is = std::cin;
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MenuState state = MenuState::MENU;
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sqlite3* db = nullptr;
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std::string userInput;
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for (;;) {
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userInput.clear();
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try {
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os << BOLDWHITE << MENU_MSG << RESET;
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is >> state;
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is.clear();
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is.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
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switch (state) {
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case MenuState::CONNECT :
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dbConnect(&db, os);
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break;
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case MenuState::QUERY_CUSTOM :
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os << "> ";
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std::getline(is, userInput);
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if(is.bad()) throw DatabaseException("Input error!");
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sendQuery(db, os, userInput.c_str(), printQuery);
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break;
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case MenuState::QUERY_PREPARED :
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os << "Account number: ";
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os << GREEN << "Balance: " << "$" << "\n" << RESET;
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break;
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case MenuState::SETUP_DEMO :
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setupDemo(&db, os);
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break;
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case MenuState::EXIT :
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os << "Exiting...\n";
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sqlite3_close(db);
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return EXIT_SUCCESS;
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break;
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case MenuState::MENU :
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default:
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throw InvalidArgument();
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}
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} catch (DatabaseException& e) {
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os << RED << e.what() << RESET;
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// return EXIT_FAILURE;
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}
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state = MenuState::MENU;
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os << "\n\n";
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}
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return EXIT_SUCCESS;
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}
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