Tutorial by Examples: s

Accessing lists

Member member/2 has signature member(?Elem, ?List) and denotes true if Elem is a member of List. This predicate can be used to access variables in a list, where different solutions are retrieved through backtracking. Example queries: ?- member(X, [1,2,3]). X = 1 ; X = 2 ; X = 3. ?- member(X...

Prolog Language • Reasoning about data

Simulate call

To simulate a phone call, press the 'Extended controls' button indicated by three dots, choose 'Phone' and select 'Call'. You can also optionally change the phone number.

Android • Emulator

Optional parameters and named arguments

We can omit the argument in the call if that argument is an Optional Argument Every Optional Argument has its own default value It will take default value if we do not supply the value A default value of a Optional Argument must be a Constant expression. Must be a value type such as enum or s...

C# Language • C# 4.0 Features

Optional ref keyword when using COM

The ref keyword for callers of methods is now optional when calling into methods supplied by COM interfaces. Given a COM method with the signature void Increment(ref int x); the invocation can now be written as either Increment(0); // no need for "ref" or a place holder variable any m...

C# Language • C# 4.0 Features

Translating a LINQ query to a SQL query

The IQueryable and IQueryable<T> interfaces allows developers to translate a LINQ query (a 'language-integrated' query) to a specific datasource, for example a relational database. Take this LINQ query written in C#: var query = from book in books where book.Author == "Steph...

C# Language • IQueryable interface

Search for nodes with name as Light, Device or Sensor

XML <Galaxy> <Light>sun</Light> <Device>satellite</Device> <Sensor>human</Sensor> <Name>Milky Way</Name> </Galaxy> XPATH /Galaxy/*[local-name()='Light' or local-name()='Device' or local-name()='Sensor'] or //*[...

xpath • Select nodes with names equal to or containing some string

Search for nodes that has name that contains Light

XML <Data> <BioLight> <name>Firefly</name> <model>Insect</model> </BioLight> <ArtificialLight> <name>Fire</name> <model>Natural element</model> <source>flint<...

xpath • Select nodes with names equal to or containing some string

Search for nodes that has name that starts with Star

XML <College> <FootBall> <Members>20</Members> <Coach>Archie Theron</Coach> <Name>Wild cats</Name> <StarFootballer>David Perry</StarFootballer> </FootBall> <Academics> ...

xpath • Select nodes with names equal to or containing some string

Search for nodes that has name that ends with Ball

XML <College> <FootBall> <Members>20</Members> <Coach>Archie Theron</Coach> <Name>Wild cats</Name> <StarPlayer>David Perry</StarPlayer> </FootBall> <VolleyBall> <Me...

xpath • Select nodes with names equal to or containing some string

Search for nodes with name light (case insensitive)

XML <Galaxy> <Light>sun</Light> <Device>satellite</Device> <Sensor>human</Sensor> <Name>Milky Way</Name> </Galaxy> XPATH /Galaxy/*[lower-case(local-name())="light"] or //*[lower-case(local-name())=&qu...

xpath • Select nodes with names equal to or containing some string

Functions with an Unknown Number of Arguments (variadic functions)

To create a function which accepts an undetermined number of arguments, there are two methods depending on your environment. 5 Whenever a function is called, it has an Array-like arguments object in its scope, containing all the arguments passed to the function. Indexing into or iterating over th...

JavaScript • Functions

Find nodes with a specific attribute

XML <Galaxy> <name>Milky Way</name> <CelestialObject name="Earth" type="planet"/> <CelestialObject name="Sun" type="star"/> </Galaxy> XPATH /Galaxy/*[@name] or //*[@name] OUTPUT <CelestialObje...