Nested Namespace Declaration

#include <iostream>
using namespace std;

namespace Config {
    namespace ADC { int resolution = 12; }
    namespace PWM { int frequency = 1000; }
}

int main() {
    cout << "ADC.resolution=" << Config::ADC::resolution << 
        "\nPWM.frequency=" << Config::PWM::frequency;
    return 0;
}