Tutorial by Examples: on

A a pointer to a piece of memory containing n elements may only be dereferenced if it is in the range memory and memory + (n - 1). Dereferencing a pointer outside of that range results in undefined behavior. As an example, consider the following code: int array[3]; int *beyond_array = array + 3; ...

Requirements: OS X 10.8 “Mountain Lion” or newer required to run Docker. While the docker binary can run natively on Mac OS X, to build and host containers you need to run a Linux virtual machine on the box. 1.12.0 Since version 1.12 you don't need to have a separate VM to be installed, as Docker...

Binaries Lua binaries are provided by most GNU/Linux distributions as a package. For example, on Debian, Ubuntu, and their derivatives it can be acquired by executing this: sudo apt-get install lua50 sudo apt-get install lua51 sudo apt-get install lua52 There are some semi-of...

Since Groups are "numbered" some engines also support matching what a group has previously matched again. Assuming you wanted to match something where two equals strings of length three are divided by a $ you'd use: (.{3})\$\1 This would match any of the following strings: "abc$...

Evaluates its first operand, and, if the resulting value is not equal to zero, evaluates its second operand. Otherwise, it evaluates its third operand, as shown in the following example: a = b ? c : d; is equivalent to: if (b) a = c; else a = d; This pseudo-code represents it : c...

This example uses the Car Table from the Example Databases. SELECT * FROM Cars WHERE TotalCost IN (100, 200, 300) This query will return Car #2 which costs 200 and Car #3 which costs 100. Note that this is equivalent to using multiple clauses with OR, e.g.: SELECT * FROM Cars WHERE TotalCos...

In order to get const char* access to the data of a std::string you can use the string's c_str() member function. Keep in mind that the pointer is only valid as long as the std::string object is within scope and remains unchanged, that means that only const methods may be called on the object. C++1...

The lambda keyword creates an inline function that contains a single expression. The value of this expression is what the function returns when invoked. Consider the function: def greeting(): return "Hello" which, when called as: print(greeting()) prints: Hello This can ...

This example shows the usage of the ILGenerator by generating code that makes use of already existing and new created members as well as basic Exception handling. The following code emits a DynamicAssembly that contains an equivalent to this c# code: public static class UnixTimeHelper { priva...

Before publishing a package you have to version it. npm supports semantic versioning, this means there are patch, minor and major releases. For example, if your package is at version 1.2.3 to change version you have to: patch release: npm version patch => 1.2.4 minor release: npm version min...

This demonstrates a filter on a for-loop, and the use of yield to create a 'sequence comprehension': for ( x <- 1 to 10 if x % 2 == 0) yield x The output for this is: scala.collection.immutable.IndexedSeq[Int] = Vector(2, 4, 6, 8, 10) A for comprehension is useful when you need to crea...

git cherry-pick <commit-hash> will apply the changes made in an existing commit to another branch, while recording a new commit. Essentially, you can copy commits from branch to branch. Given the following tree (Source) dd2e86 - 946992 - 9143a9 - a6fd86 - 5a6057 [master] \ ...

Go is a statically typed language, meaning you generally have to declare the type of the variables you are using. // Basic variable declaration. Declares a variable of type specified on the right. // The variable is initialized to the zero value of the respective type. var x int var s string va...

The ls command's -l option prints a specified directory's contents in a long listing format. If no directory is specified then, by default, the contents of the current directory are listed. ls -l /etc Example Output: total 1204 drwxr-xr-x 3 root root 4096 Apr 21 03:44 acpi -rw-r--r-- 1 r...

The first operand must be a function pointer (a function designator is also acceptable because it will be converted to a pointer to the function), identifying the function to call, and all other operands, if any, are collectively known as the function call's arguments. Evaluates into the return valu...

The X-macro approach can be generalized a bit by making the name of the "X" macro an argument of the master macro. This has the advantages of helping to avoid macro name collisions and of allowing use of a general-purpose macro as the "X" macro. As always with X macros, the mas...

docker run hello-world This will fetch the latest hello-world image from the Docker Hub (if you don't already have it), create a new container, and run it. You should see a message stating that your installation appears to be working correctly.

docker run docker/whalesay cowsay 'Hello, StackExchange!' This command tells Docker to create a container from the docker/whalesay image and run the command cowsay 'Hello, StackExchange!' in it. It should print a picture of a whale saying Hello, StackExchange! to your terminal. If the entrypoin...

Normally, a Docker container persists after it has exited. This allows you to run the container again, inspect its filesystem, and so on. However, sometimes you want to run a container and delete it immediately after it exits. For example to execute a command or show a file from the filesystem. Dock...

The "default" for constructors is that they do not have any arguments. In case you do not specify any constructor, the compiler will generate a default constructor for you. This means the following two snippets are semantically equivalent: public class TestClass { private String tes...