Small Project Organization

Namespace Helpers

A namespace groups helper names so a small project can avoid accidental collisions.

namespace Namespaces give related functions a shared prefix without putting everything into one global name pool.
qualification Calling `billing::addFee` makes the helper's ownership visible at the call site.

Namespace Helpers

subtotal
namespace_helpers.cpp
Replay: real traced execution (multi-file project)
#include <iostream>

namespace billing {
int addFee(int amount, int fee) {
    return amount + fee;
}
}

int main() {
    int subtotal = 35;

    int fee = 4;
    int total = billing::addFee(subtotal, fee);

    std::cout << "subtotal=" << subtotal << std::endl;
    std::cout << "fee=" << fee << std::endl;
    std::cout << "total=" << total << std::endl;
    return 0;
}

#include <iostream>

namespace billing {
int addFee(int amount, int fee) {
    return amount + fee;
}
}

int main() {
    int subtotal = 10;

    int fee = 4;
    int total = billing::addFee(subtotal, fee);

    std::cout << "subtotal=" << subtotal << std::endl;
    std::cout << "fee=" << fee << std::endl;
    std::cout << "total=" << total << std::endl;
    return 0;
}

#include <iostream>

namespace billing {
int addFee(int amount, int fee) {
    return amount + fee;
}
}

int main() {
    int subtotal = 80;

    int fee = 4;
    int total = billing::addFee(subtotal, fee);

    std::cout << "subtotal=" << subtotal << std::endl;
    std::cout << "fee=" << fee << std::endl;
    std::cout << "total=" << total << std::endl;
    return 0;
}

  1. subtotal ← 35, fee ← 4

    9int main() {10    int subtotal→ 35 = 35; //@subtotal=10, 801112    int fee→ 4 = 4;13    int total = billing::addFee(subtotal35, fee4);

  2. int addFee(int amount, int fee)

    3namespace billing {4int addFee(int amount35, int fee4) {5    return amount35 + fee4;6}

  3. total ← 39

    12    int fee = 4;13    int total→ 39 = billing::addFee(subtotal35, fee4);1415    std::cout << "subtotal=" << subtotal35 << std::endl;16    std::cout << "fee=" << fee4 << std::endl;17    std::cout << "total=" << total39 << std::endl;18    return 0;19}
    outputsubtotal=35
fee=4
total=39

  1. subtotal ← 10, fee ← 4

    9int main() {10    int subtotal→ 10 = 10;1112    int fee→ 4 = 4;13    int total = billing::addFee(subtotal10, fee4);

  2. int addFee(int amount, int fee)

    3namespace billing {4int addFee(int amount10, int fee4) {5    return amount10 + fee4;6}

  3. total ← 14

    12    int fee = 4;13    int total→ 14 = billing::addFee(subtotal10, fee4);1415    std::cout << "subtotal=" << subtotal10 << std::endl;16    std::cout << "fee=" << fee4 << std::endl;17    std::cout << "total=" << total14 << std::endl;18    return 0;19}
    outputsubtotal=10
fee=4
total=14

  1. subtotal ← 80, fee ← 4

    9int main() {10    int subtotal→ 80 = 80;1112    int fee→ 4 = 4;13    int total = billing::addFee(subtotal80, fee4);

  2. int addFee(int amount, int fee)

    3namespace billing {4int addFee(int amount80, int fee4) {5    return amount80 + fee4;6}

  3. total ← 84

    12    int fee = 4;13    int total→ 84 = billing::addFee(subtotal80, fee4);1415    std::cout << "subtotal=" << subtotal80 << std::endl;16    std::cout << "fee=" << fee4 << std::endl;17    std::cout << "total=" << total84 << std::endl;18    return 0;19}
    outputsubtotal=80
fee=4
total=84