Namespaces and Organization

Qualified Names

The :: operator chooses a name from a specific namespace.

qualified name A qualified name includes the namespace, `::`, and the name to use.

Qualified Names

totalCents
qualified_names.cpp
Replay: real traced execution (multi-file project)
#include <iostream>
#include <string>

namespace checkout {
std::string status(int cents) {
    if (cents >= 1000) {
        return "large";
    }
    return "small";
}
}

int main() {
    int totalCents = 750;

    std::string size = checkout::status(totalCents);

    std::cout << "totalCents=" << totalCents << std::endl;
    std::cout << "status=" << size << std::endl;
    return 0;
}

#include <iostream>
#include <string>

namespace checkout {
std::string status(int cents) {
    if (cents >= 1000) {
        return "large";
    }
    return "small";
}
}

int main() {
    int totalCents = 250;

    std::string size = checkout::status(totalCents);

    std::cout << "totalCents=" << totalCents << std::endl;
    std::cout << "status=" << size << std::endl;
    return 0;
}

#include <iostream>
#include <string>

namespace checkout {
std::string status(int cents) {
    if (cents >= 1000) {
        return "large";
    }
    return "small";
}
}

int main() {
    int totalCents = 1200;

    std::string size = checkout::status(totalCents);

    std::cout << "totalCents=" << totalCents << std::endl;
    std::cout << "status=" << size << std::endl;
    return 0;
}

  1. totalCents ← 750

    13int main() {14    int totalCents→ 750 = 750; //@totalCents=1200, 2501516    std::string size = checkout::status(totalCents750);

  2. std::string status(int cents)

    4namespace checkout {5std::string status(int cents750) {6    if (cents >= 1000) {7        return "large";8    }9    return "small";10}

  3. size ← small

    16    std::string size→ small = checkout::status(totalCents750);1718    std::cout << "totalCents=" << totalCents750 << std::endl;19    std::cout << "status=" << sizesmall << std::endl;20    return 0;21}
    outputtotalCents=750
status=small

  1. totalCents ← 250

    13int main() {14    int totalCents→ 250 = 250;1516    std::string size = checkout::status(totalCents250);

  2. std::string status(int cents)

    4namespace checkout {5std::string status(int cents250) {6    if (cents >= 1000) {7        return "large";8    }9    return "small";10}

  3. size ← small

    16    std::string size→ small = checkout::status(totalCents250);1718    std::cout << "totalCents=" << totalCents250 << std::endl;19    std::cout << "status=" << sizesmall << std::endl;20    return 0;21}
    outputtotalCents=250
status=small

  1. totalCents ← 1200

    13int main() {14    int totalCents→ 1200 = 1200;1516    std::string size = checkout::status(totalCents1200);

  2. std::string status(int cents)

    4namespace checkout {5std::string status(int cents1200) {6    if (cents >= 1000) {

  3. if (cents >= 1000)

    5std::string status(int cents) {6    if (cents1200 >= 1000) {7        return "large";8    }

  4. size ← large

    16    std::string size→ large = checkout::status(totalCents1200);1718    std::cout << "totalCents=" << totalCents1200 << std::endl;19    std::cout << "status=" << sizelarge << std::endl;20    return 0;21}
    outputtotalCents=1200
status=large