Mar 06 In-Class

Note

There are no wrong answers. This is for participation credit, and is intended to let me know how well we understand the material at this point.

Access the form: https://forms.gle/AdFzxiuRLXWZjnF87

Question 1

Consider the following code:

std::vector<int> vec{1, 2, 3, 4, 5};

for (auto e : vec) {
    // do something with e
}

As written, in the loop we cannot modify the value of e. How do we change this to let us modify e?

solution

We need to use a reference when accessing the element of the vector. This means modifying the loop to be:

for (auto &e : vec) {
    // do something with e
}

Question 2

Consider the following struct representing a 3D Cartesian mathematical vector (with \(x\), \(y\), and \(z\) components):

struct MathVector {
    double x{};
    double y{};
    double z{};
};

How do you create a MathVector called v and initialize it with \((x, y, z) = (1, 2, 3)\)?

solution

We would do any of the following:

MathVector v{1, 2, 3};

MathVector v{.x=1, .y=2, .z=3};

MathVector v;
v.x = 1;
v.y = 2;
v.z = 3;