NuGet has recently added support for native projects. This simplifies a lot deployment of native libraries. Even though cpplinq is not a big library (in fact is just a header file) I have created a NuGet package so that you are able to automatically add it to your project.

Here is what you have to do.

  1. Make sure you have NuGet 2.5 or newer, otherwise the NuGet package manager won’t show up in your VC++ projects.
  2. In the context menu for your project choose Manage NuGet Packages…
    cpplinqdemo1
  3. Search for cpplinq and install the package.
    cpplinqdemo2
  4. Include the cpplinq.hpp header and start using the library. Here is a sample to test that everything is all right.

Notice that all the settings for library (such as adding the proper entry for the include directories or defining NOMINMAX so that min and max macros will not be defined for the project) are automatically performed, so you can focus on coding.

, , , , , , , Hits for this post: 40647 .

cpplinq: set operators

In the previous posts I introduced cpplinq, a C++ template library that provides .NET-like query operators for sequences of objects in C++11. In this third installment I will discuss the set operators the library provides.

There are four set operators: distinct, union_with (called so because union is a keyword in C++), intersect_with (suffix _with is for consistency with the union operator) and except. These operators should be pretty straight forward: distinct eliminates the duplicate elements from a sequence, yielding a new sequence with only the distinct elements (in the order their original order), union_with produces the set union of two sequences, intersect_with produces the set intersection of two sequences and except produces the set difference of two sequences.

Before seeing some examples, it worth nothing that all these operators delay the traversal of the sequences until the resulting object is enumerated.

Let’s see some examples:

You can learn more about these operators (and the others that are implemented) by reading the cpplinq query operators documentation.

, , , , , Hits for this post: 30070 .

In my previous post I introduced cpplinq, a C++ template library that provides .NET-like query operators for sequences of objects in C++11. In this second installment I will discuss about two things: range generators and range conversion operators. These two sets of operators are ubiquitous in queries.

Range generators

A range generator builds an object that represents the range on which query operators are applied. The library provides several such generators:

  • from_iterators: constructs a range from a pair of iterators
  • from: constructs a range from an STL-like container that provides begin() and end() methods (representing the first and past-the-end elements). This is basically a wrapper on from_iterators operator.

    This is similar to:
  • from_array: constructs a range from an array.

    This is similar to:

In addition to the “from” operators, the library also provides several .NET like range generators:

  • range: generates a range of integral, consecutive numbers, starting with an initial seed and having a specified number of elements.
  • repeat: generates a range by repeating a value a given number of times
  • empty: returns an empty range of a given type

Range conversion operators

A conversion operator folds a range into a container that holds the values of the range. There are several such conversion operators that the library provides.

  • to_vector: creates a std::vector<TValue> from a range, where TValue is the type of the elements of the range.
  • to_list: creates a std::list<TValue> from a range, where TValue is the type of the elements of the range.
  • to_map: creates a std::map<TKey, TValue> from a range. It takes a predicate that selects the value to use as the key for each element of the range. It implements a one-to-one dictionary that maps keys to single values.
  • to_lookup: creates a cpplinq::lookup<TKey, TElement> from a sequence. It implements a one-to-many dictionary that maps keys to sequences of values.

, , , , , , , Hits for this post: 28867 .

cpplinq: An introduction

cpplinq is a C++ template library that provides .NET-like query operators for sequences of objects in C++11. cpplinq is an open-source library that works both with VC++ compilers (2010 and 2012) and gcc (4.7.0 is the version used for unit tests). The library supports most of the .NET query operators and is extendable with additional operators that can suite some particular use. If you’re not familiar with .NET query operators, this article, http://msdn.microsoft.com/en-us/library/bb394939.aspx, lists and explain them.

The light-weighted library consists of a series of template classes and helper methods, provided in a single header under the namespace cpplinq.

This is a short introduction to the library. More posts will follow. Let’s see some examples.

The following code retrieves all the prime numbers from an array.

A slightly variation produces a sequence of first N prime numbers and transforms them into strings.

The next sample retrieves all the orders from a customer.

Callinq print_orders_by_cust() with argument 1 would print:

On the other hand, if you want to print the last order from a particular customer, the function above would change to something like this:

Calling print_last_order_for_customer() with argument 1 would print:

Hopefully this provides a quick view over the capabilities of the library. In following posts I will show more examples and discuss some of the query operators. To learn more about the library see the following articles:

, , , , , Hits for this post: 36158 .

I’ve ran recently across this question: how to find (using C++) if a computer is a laptop? That is possible with WMI and many answers (such as this) point to the Win32_SystemEnclosure class. This class has a member called ChassisTypes, which is an array of integers indicating possible chassis types. At least one of them should indicate a laptop. However, there might be several problems with this solution. First, there are several values for “laptops”:

  • 8 – Portable
  • 9 – Laptop
  • 10 – Notebook

Different machines might return different values. And more important, this property might not be defined on all computers. A more reliable solution is explained in this TechNet article Finding Computers That Are Laptops. The solution described there suggests checking for several properties:

  • Win32_SystemEnclosure, ChassisTypes(1)=10.
  • Win32_Battery or Win32_PortableBattery.
  • Win32_PCMCIAController
  • Win32_DriverVXD.Name = “pccard”
  • Win32_ComputerSystem.Manufacturer
  • Win32_ComputerSystem.Model

The following code shows how one can query for the chassis types using C++. Run queries for the other properties to make sure you are running on a laptop.

On my laptop, the program output was:

Name: System Enclosure
Chassis: Notebook

, , , Hits for this post: 39125 .