# 10.18. Activecode Exercises¶

Answer the following **Activecode** questions to assess what you have learned in this chapter.

Fix the code below so that it creates a vector with 5 elements initialized to 1, and changes the third element of that vector to a 2.

Below is one way to fix the program. You must always include the `<vector>`

header when
dealing with vectors. Furthermore, to initialize a vector’s elements to a certain value, you
must include that value as a second argument to the size. Finally, vectors are zero-indexed.

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Selecting from: vectors_a2, vectors_a2_pp

Fix the function below so that it creates a vector of all of the words in `words`

that end with
the passed character.

Below is one way to fix the function. You must initialize `count`

to zero.
You also must initialize `last`

as an integer. To access a string *inside*
of `vec`

, we use `vec[i]`

. To get the last character, we must index the
string to the last index, which is one less than the length of the string.

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Selecting from: vectors_a4, vectors_a4_pp

Finish the code below so that it creates removes elements from the end of the vector until
it ends with `"stop"`

.

Below is one way to finish the program. We just use the `pop_back`

function until the
last element of the vector is `"stop"`

.

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Selecting from: vectors_a6, vectors_a6_pp

Write a function called `has_char`

that returns a boolean of whether every string in the
vector `vec`

contains the character `let`

. It should return true if all strings contain the `let`

.

Below is one way to finish the program. We loop through the vector, and we loop through each string
inside it. If the string has the character, it is added to `count`

. We then check whether `count`

is equal to the number of elements in `vec`

and return a boolean.

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Selecting from: vectors_a8, vectors_a8_pp

Write the function `mean`

which returns the average of a vector of numbers.

Below is one way to finish the program. First we take the sum, then divide the sum by the number
of elements in `nums`

.

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Selecting from: vectors_a10, vectors_a10_pp

Write the function `make_odd`

which subtracts 1 from every even number in a vector of integers.
We don’t want any negative values so don’t subtract 1 from 0.
( remember to take in the vector by reference to make changes to the actual vector! )

Below is one way to finish the program. We us the modulus operator to check for even numbers and decrement them. we keep an extra check for 0 to make sure wew are not decrementing 0.

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Selecting from: vectors_a12, vectors_a12_pp