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Vectors
Index

Now that we have a vector, how do we access an individual element? This is where index comes into play.

An index refers to an element’s position within an ordered list. Vectors are 0-indexed, meaning the first element has index 0, the second index 1, and so on.

For example, suppose we have a char vector with all the vowels:

std::vector<char> vowels = {'a', 'e', 'i', 'o', 'u'};

It should look something like this:

vowels

  • The character at index 0 is 'a'.
  • The character at index 1 is 'e'.
  • The character at index 2 is 'i'.
  • The character at index 3 is 'o'.
  • The character at index 4 is 'u'.

To output each of the elements, we can do:

std::cout << vowels[0] << "\n"; std::cout << vowels[1] << "\n"; std::cout << vowels[2] << "\n"; std::cout << vowels[3] << "\n"; std::cout << vowels[4] << "\n";

Using the notation vector[index] with square brackets after the vector name and the element’s index number inside.

This will output:

a e i o u

Instructions

1.

What is the element at index 2 in the subway_child vector?

Find out the answer by outputting it out using std::cout.

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