5  Indirection

5.1 Pointers

include <iostream>

int main(int argc, char const *argv[])
{
    int i = 5;
    int *p1 = &i;
    int *p2 = new int;

    std::cout << "i: " << i << std::endl
              << "*p1: " << *p1 << std::endl
              << "p1: " << p1 << std::endl
              << "&p1: " << &p1 << std::endl
              << "p2: " << p2 << std::endl
              << "*p2: " << *p2 << std::endl;
    delete p2;
    return 0;
}

output:

i: 5
*p1: 5
p1: 0x7fff8d568184
&p1: 0x7fff8d568188
p2: 0x55c014358eb0
*p2: 0

• release memory with delete.
• deleting too early -> bugs, too late -> memory leaks

5.2 References

References are aliases for an existing entity. k

include <iostream>

int main(int argc, const char** argv) {

    int a = 4;
    std::cout << "a: " << a <<std::endl;
    int &b = a;
    b = 5;
    std::cout << "a: " << a << std::endl
              << "b: " << b << std::endl;

    return 0;
}

output:

a: 4
a: 5
b: 5

5.3 Rvalue (double) References

Two uses:

• range-based for loops
• move semantics

lvalue references refer to entities, rvalue references refer to literals.