# Activecode Exercises¶

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

We have a file called “locations.txt” that we want to read data from. Check to make sure that the file was opened properly; if it wasn’t, display an error message and exit with a status of 1.

Below is one way to write code that makes sure the file was opened properly.

Let’s write a program that prompts the user for a filename and opens that file.

Below is one way to write the program.

Now let’s write some output to a file. Write a program that prompts a user for a list of 5 integers separated by spaces, calculates the average of those integers, and outputs “The average is `average`” to an output file called “average.txt”. Put the necessary blocks of code in the correct order. Declare the output file first and check that it is opened correctly.

Below is one way to write the program.

We are given a file called “data.txt” with an unknown number of `double` values. Write a program that finds the minimum, maximum, and number of data and outputs these values to a file called “summary.txt”. Declare the input and output files first, and check to see that both are opened correctly before dealing with data. Increment the number of data points before checking for the min and max.

Below is one way to write the code.

You are given a file called “employee_data.txt” and you want to store the information from that file into a vector of data. The file contains information about an employee’s first and last name, age, phone number, and email. Write the definition of an `Employee` before you write your `main` function. Open and check the file before working with the data.

Below is one way to define `Employee`.

You are given a file but it appears that someone’s capslock key was stuck because everything is in uppercase. Write a program that takes the input from the file “UPPER.txt” and converts all the words to lowercase and prints out the modified message to a file called “lower.txt”. Write the definition of the function `toLower` first. Separate the words with spaces.

Below is one way to write the program and `toLower` function.

Nobody ever put a limit on how many files we can work with. Does this mean we can open two or more files at once? Yes we can! Write a program that combines two files “odds.txt” and “evens.txt” into one output file “numbers.txt”. You should combine them in a way such that “numbers.txt” contains the first odd number then the first even number then the second odd number and so on. You are guaranteed that there are equal amounts of odd and even numbers.

Below is one way to write the prgram.

In chapter 15.7 we defined the `Set` data structure. Write a function `vectorToSet` which takes a `vector` of data and returns a `Set` object with the data. Put the `Set` definition first in your answer.

Below is one way to write the `vectorToSet` function.

Let’s write the struct definition for a `Matrix`! The underlying data structure is a `vector` of vectors of ```int``s. Write the constructor and ``at``` function, which returns the data stored at a given row and column.

Below is one way to define `Matrix` and write the functions.

Now that we have the basic structure of a `Matrix`, let’s write a function that allows us to add data to a matrix. Write the `Matrix` member function `setData` which takes a row and column index as well as a data value and stores the data value in the `Matrix` at the given location. Then read data in from a file called `data.txt`. The first line contains the number of rows and columns, separated by a space. Data values begin on the next line.

Below is one way to `setData` member function.