#include <iostream>
class DatabaseConnection {
private:
// Define a private static property using C++17 'inline static' initialization.
// This tracks active connections across all instances of the class.
inline static int activeConnections = 0;
public:
DatabaseConnection() {
// Increment the shared static counter when an object is instantiated
++activeConnections;
}
~DatabaseConnection() {
// Decrement when an object is destroyed
--activeConnections;
}
// Static member function to safely access the private static property
static int getActiveConnections() {
return activeConnections;
}
};
int main() {
// 1. Accessing static function directly via the class name (Best Practice)
std::cout << "Initial active connections: "
<< DatabaseConnection::getActiveConnections() << "\n";
{
// Create local instances within a block scope
DatabaseConnection db1;
DatabaseConnection db2;
std::cout << "Active connections inside block: "
<< DatabaseConnection::getActiveConnections() << "\n";
} // db1 and db2 are destroyed here, decrementing the counter
std::cout << "Active connections after block scope: "
<< DatabaseConnection::getActiveConnections() << "\n";
}
/*
run:
Initial active connections: 0
Active connections inside block: 2
Active connections after block scope: 0
*/
