trainings/AdvancedCppV2/Presentation/templates_knowledge_check.md

Templates

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Knowledge check

Template type deduction

template <typename T>
void copy(T arg) {}

template <typename T>
void reference(T& arg) {}

template <typename T>
void universal_reference(T&& arg) {}

int main() {
    int number = 4;
    copy(number);       // int
    copy(5);            // int
    reference(number);  // int&
    reference(5);       // candidate function [with T = int] not viable: expects an l-value for 1st argument
    universal_reference(number);            // int&
    universal_reference(std::move(number)); // int&&
    universal_reference(5);                 // int&&
}

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Knowledge check

void foo(int && a);         // r
void foo(int & a);          // l

int a = 5;

Which of above functions will be called by below snippets?

• foo(4);
  • r
• foo(a);
  • l
• foo(std::move(a));
  • r
• foo(std::move(4));
  • r (move is redundant)

---

Knowledge check

template <typename T>
void foo(T && a);         // r

template <typename T>
void foo(T & a);          // l

int a = 5;

Which of above functions will be called by below snippets?

• foo(4);
  • r
• foo(a);
  • l
• foo(std::move(a));
  • r

---

Knowledge check

template <typename T>
void foo(T && a);         // r

int a = 5;

What will happen now?

• foo(4);
  • r
• foo(a);
  • r
• foo(std::move(a));
  • r