Chapter 21 // Drill 3 - 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 - Principles & Practice Using C++

In this exercise I am using Visual Studio 2019 and a modified version of the std_lib_facilities header found here.

Chapter 21 // Drill 3.1

Read some floating-point values (at least 16 values) from a file into a vector<doubles> called vd.

Chapter 21 // Drill 3.2

Output vd to cout.

Chapter 21 // Drill 3.3

Make a vector vi of type vector<int> with the same number of elements as vd; copy the elements from vd into vi.

Chapter 21 // Drill 3.4

Output the pairs of (vd[i], vi[i]) to cout, one pair per line.

Chapter 21 // Drill 3.5

Output the sum of the elements of vd.

Chapter 21 // Drill 3.6

Output the difference between the sum of the elements of vd and the sum of the elements of vi.

Chapter 21 // Drill 3.7

There is a standard library algorithm called reverse that takes a sequence (pair of iterators) as arguments; reverse vd, and output vd to cout.

Chapter 21 // Drill 3.8

Compute the mean value of the elements in vd; output it.

Chapter 21 // Drill 3.9

Make a new vector<double> called vd2 and copy all elements of vd with values lower than (less than) the mean into vd2.

Chapter 21 // Drill 3.10

Sort vd, output it again.

Github: https://github.com/l-paz91/principles-practice/tree/master/Chapter%2021/Drill%203

With drill 9 I found out about std::copy_if():
https://en.cppreference.com/w/cpp/algorithm/copy

Chapter 21 // Drill 2 - 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 - Principles & Practice Using C++

In this exercise I am using Visual Studio 2019 and a modified version of the std_lib_facilities header found here.

Chapter 21 // Drill 2.1

Define a map<string, int> called msi.

Chapter 21 // Drill 2.2

Insert ten (name, value) pairs into it, e.g., msi["lecture"]=21.

Chapter 21 // Drill 2.3

Output the (name, value) pairs to cout in some format of your choice.

Chapter 21 // Drill 2.4

Erase the (name, value) pairs from msi.

Chapter 21 // Drill 2.5

Write a function that reads value pairs from cin and places them in msi.

Chapter 21 // Drill 2.6

Read 10 pairs from input and enter them into msi.

Chapter 21 // Drill 2.7

Write the elements of msi to cout.

Chapter 21 // Drill 2.8

Output the sum of the (integer) values in msi.

Chapter 21 // Drill 2.9

Define a map<int, string> called mis.

Chapter 21 // Drill 2.10

Enter the values from msi into mis; that is, if msi has an element ("lecture",21), mis should have an element (21, "lecture").

Chapter 21 // Drill 2.11

Output the elements of mis to cout.

Github: https://github.com/l-paz91/principles-practice/blob/master/Chapter%2021/Drill%202%20-%20All%20drills

For Drill 2.4 I wasn't sure if he meant erase a few or erase all so I went with erase all.

With Drill 2.7 I think he meant create an overload of the output operator for the map as creating a print function has already been done.

Whilst doing 2.9 I decided to make my functions more generic so they could accept maps of almost any type.

Chapter 21 // Drill 1 - 8 - Principles & Practice Using C++

In this exercise I am using Visual Studio 2019 and a modified version of the std_lib_facilities header found here.

Chapter 21 // Drill 1.8

Repeat the exercise with a list<Item> rather than a vector<Item>.

Github: https://github.com/l-paz91/principles-practice/blob/master/Chapter%2021/Drill%201/Drill%208

I had to do two minimal things to get this work;

1 - Use advance instead of It + num.

2 - Use the sort() provided by the list container instead of just the standard one.

Chapter 21 // Drill 1 - 1, 2, 3, 4, 5, 6, 7 - Principles & Practice Using C++

In this exercise I am using Visual Studio 2019 and a modified version of the std_lib_facilities header found here.

Chapter 21 // Drill 1.1

Define struct Item { string name; int iid; double value; /* ... */};, make a vector<Item>, vi, and fill it with ten items from a file.

Chapter 21 // Drill 1.2

Sort vi by name.

Chapter 21 // Drill 1.3

Sort vi by iid.

Chapter 21 // Drill 1.4

Sort vi by value; print it in order of decreasing value (i.e., largest value first).

Chapter 21 // Drill 1.5

Insert Item{"horse shoe", 99, 12.34} and Item{"Canon S400", 9988, 499.95}.

Chapter 21 // Drill 1.6

Remove (erase) two Items identified by name from vi.

Chapter 21 // Drill 1.7

Remove (erase) two Items identified by iid from vi.

Github: 

https://github.com/l-paz91/principles-practice/blob/master/Chapter%2021/Drill%201/Drill%201%2C2%2C3%2C4%2C5%2C6%2C7

New things all around in this exercise. I used the code from page 791 to start with and added operator>> to Item so I didn't have to modify it. This worked perfectly and vector happily constructed 10 Items using the data from the text file thanks to the operator overload. The input code is a bit hardcoded however it allows Items to have spaces in the name value as it uses getline().

For the second drill I tried my hand at creating a function object to sort the name. They are very easy to use.

For sorting by value I allowed a bool to passed to the function object which allows it to switch between increasing/decreasing order.

Whilst doing Drill 6 I also found out that std::remove_if will erase a member of a custom object when passed a predicate to find that member; very cool.