Tutorial by Examples: st

Some people recommend that you should apply various tests to a file before attempting to open it either to provide better diagnostics or avoid dealing with exceptions. For example, this method attempts to check if path corresponds to a readable file: public static File getValidatedFile(String path...

Detailed instructions on getting x++ set up or installed.

Using the Package Manager JDK and/or JRE releases for OpenJDK or Oracle can be installed using the package manager on most mainstream Linux distribution. (The choices that are available to you will depend on the distro.) As a general rule, the procedure is to open terminal window and run the comm...

Only Oracle JDKs and JREs are available for Windows platforms. The installation procedure is straight-forward: Visit the Oracle Java Downloads page: Click on either the JDK button, the JRE button or the Server JRE button. Note that to develop using Java you need JDK. To know the difference betw...

Oracle Java 7 and Java 8 Java 7 and Java 8 for macOS are available from Oracle. This Oracle page answers a lot of questions about Java for Mac. Note that Java 7 prior to 7u25 have been disabled by Apple for security reasons. In general, Oracle Java (Version 7 and later) requires an Intel-based Mac...

Sometimes you may need to convert a Set to an array, for example to be able to use Array.prototype methods like .filter(). In order to do so, use Array.from() or destructuring-assignment: var mySet = new Set([1, 2, 3, 4]); //use Array.from const myArray = Array.from(mySet); //use destructuring-a...

To export the type and all its constructors, one must use the following syntax: module X (Person (..)) where So, for the following top-level definitions in a file called People.hs: data Person = Friend String | Foe deriving (Show, Eq, Ord) isFoe Foe = True isFoe _ = False This module d...

zip takes two lists and returns a list of corresponding pairs: zip [] _ = [] zip _ [] = [] zip (a:as) (b:bs) = (a,b) : zip as bs > zip [1,3,5] [2,4,6] > [(1,2),(3,4),(5,6)] Zipping two lists with a function: zipWith f [] _ = [] zipWith f _ [] =...

Classes, structs, enums and all their methods are internal by default. This means they can be only accessed from the same module. The test cases are in a different target an this means they are in a different module. To be able to access the method you want to test, you need to import the module to ...

In its simplest form supported by all versions of bash, case statement executes the case that matches the pattern. ;; operator breaks after the first match, if any. #!/bin/bash var=1 case $var in 1) echo "Antartica" ;; 2) echo "Brazil" ;; 3) echo "Cat&qu...

4.0 Since bash 4.0, a new operator ;& was introduced which provides fall through mechanism. #!/bin/bash var=1 case $var in 1) echo "Antartica" ;& 2) echo "Brazil" ;& 3) echo "Cat" ;& esac Outputs: Antartica Brazil Cat ...

This creates a variant (a tagged union) that can store either an int or a string. std::variant< int, std::string > var; We can store one of either type in it: var = "hello"s; And we can access the contents via std::visit: // Prints "hello\n": visit( [](auto&&a...

This does not cover allocators. struct A {}; struct B { B()=default; B(B const&)=default; B(int){}; }; struct C { C()=delete; C(int) {}; C(C const&)=default; }; struct D { D( std::initializer_list<int> ) {}; D(D const&)=default; D()=default; }; std::variant<A,B> var_ab...

The original C standard had no intrinsic Boolean type, so bool, true and false had no inherent meaning and were often defined by programmers. Typically true would be defined as 1 and false would be defined as 0. C99 C99 adds the built-in type _Bool and the header <stdbool.h> which defines bo...

In R, data objects are manipulated using named data structures. The names of the objects might be called "variables" although that term does not have a specific meaning in the official R documentation. R names are case sensitive and may contain alphanumeric characters(a-z,A-z,0-9), the dot...

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5.6 PHP 5.6 introduced variable-length argument lists (a.k.a. varargs, variadic arguments), using the ... token before the argument name to indicate that the parameter is variadic, i.e. it is an array including all supplied parameters from that one onward. function variadic_func($nonVariadic, ...$...

The Repeat command, executed with the dot or period key (.), is more useful than it first appears. Once learned, you will find yourself using it often. Command:Description.Repeat the last change10.Repeat the last change 10 times So then, for a very simple example, if you make a change to line 1 by...

In Vim, these operations are handled differently from what you might be used to in almost any other modern editor or word processor (Ctrl-C, Ctrl-X, Ctrl-V). To understand, you need to know a little about registers and motions. Note: this section will not cover Visual Mode copying and cutting or ra...

C++17 A storage class specifier that hints to the compiler that a variable will be heavily used. The word "register" is related to the fact that a compiler might choose to store such a variable in a CPU register so that it can be accessed in fewer clock cycles. It was deprecated starting ...