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Inheritance - Abstract and Final Methods and Classes

Information The ABSTRACT and FINAL additions to the METHODS and CLASS statements allow you to define abstract and final methods or classes. An abstract method is defined in an abstract class and cannot be implemented in that class. Instead, it is implemented in a subclass of the class. Abstra...

Assertion of Unreachable Code

During development, when certain code paths must be prevented from the reach of control flow, you may use assert(0) to indicate that such a condition is erroneous: switch (color) { case COLOR_RED: case COLOR_GREEN: case COLOR_BLUE: break; default: assert(0); ...

Assert Error Messages

A trick exists that can display an error message along with an assertion. Normally, you would write code like this void f(void *p) { assert(p != NULL); /* more code */ } If the assertion failed, an error message would resemble Assertion failed: p != NULL, file main.c, line 5 Ho...

Basic Note Outputs

#define NOTE_C4 262 //From pitches.h file defined in [Arduino Tone Tutorial][1] int Key = 2; int KeyVal = 0; byte speaker = 12; void setup() { pinMode(Key, INPUT); //Declare our key (button) as input pinMode(speaker, OUTPUT); } void loop() { KeyVal = digitalRead(Key); i...

Escaping curly brackets inside a String.Format() expression

string outsidetext = "I am outside of bracket"; string.Format("{{I am in brackets!}} {0}", outsidetext); //Outputs "{I am in brackets!} I am outside of bracket"

Using ngStorage to share data

Firstly, include the ngStorage source in your index.html. An example injecting ngStorage src would be: <head> <title>Angular JS ngStorage</title> <script src = "http://ajax.googleapis.com/ajax/libs/angularjs/1.3.14/angular.min.js"></script> &l...

Installation or Setup

Linux kernel source code can be found in https://www.kernel.org/ Download extract and enter to the kernel directory Type these commands step by steps in your terminal.(Choose the appropriate version you needed instead of linux-4.7.tar.gz ) wget http://www.kernel.org/pub/linux/kernel/v4.7/linux-4....

IronPython is written in pure c#

IronPython is completly written using managed .net (c#) code. So all builtin python methods and libraries (such as next(), int(), etc.) are writtin in .net. This example shows the implementation of len() for a list of different types (only a few): .... public static int len([NotNull]List/*!*/ l...

Vector Iterator

begin returns an iterator to the first element in the sequence container. end returns an iterator to the first element past the end. If the vector object is const, both begin and end return a const_iterator. If you want a const_iterator to be returned even if your vector is not const, you can use ...

Map Iterator

An iterator to the first element in the container. If a map object is const-qualified, the function returns a const_iterator. Otherwise, it returns an iterator. // Create a map and insert some values std::map<char,int> mymap; mymap['b'] = 100; mymap['a'] = 200; mymap['c'] = 300; // It...

Declaring permissions in your manifest file

Any permission required by your application to access a protected part of the API or to interact with other applications must be declared in your AndroidManifest.xml file. This is done using the <uses-permission /> tag. Syntax <uses-permission android:name="string" android...

Const local variables

Declaration and usage. // a is const int, so it can't be changed const int a = 15; a = 12; // Error: can't assign new value to const variable a += 1; // Error: can't assign new value to const variable Binding of references and pointers int &b = a; // Error: ca...

Const pointers

int a = 0, b = 2; const int* pA = &a; // pointer-to-const. `a` can't be changed through this int* const pB = &a; // const pointer. `a` can be changed, but this pointer can't. const int* const pC = &a; // const pointer-to-const. //Error: Cannot assign to a const reference *pA = b...

Return in a lock statement

Following code will release lock. lock(locker) { return 5; } For a detailed explanation, this SO answer is recommended.

Mistakenly writing = instead of == when comparing

The = operator is used for assignment. The == operator is used for comparison. One should be careful not to mix the two. Sometimes one mistakenly writes /* assign y to x */ if (x = y) { /* logic */ } when what was really wanted is: /* compare if x is equal to y */ if (x == y) { ...

Incautious use of semicolons

Be careful with semicolons. Following example if (x > a); a = x; actually means: if (x > a) {} a = x; which means x will be assigned to a in any case, which might not be what you wanted originally. Sometimes, missing a semicolon will also cause an unnoticeable problem: if (i &lt...

Matplotlib

Matplotlib is a mathematical plotting library for Python that provides a variety of different plotting functionality. The matplotlib documentation can be found here, with the SO Docs being available here. Matplotlib provides two distinct methods for plotting, though they are interchangable for the...

Getting a shell into a running (detached) container

Log into a running container A user can enter a running container in a new interactive bash shell with exec command. Say a container is called jovial_morse then you can get an interactive, pseudo-TTY bash shell by running: docker exec -it jovial_morse bash Log into a running container with a s...

Instance methods

An instance method is a method that's available on a particular instance of a class, after the instance has been instantiated: MyClass *instance = [MyClass new]; [instance someInstanceMethod]; Here's how you define one: @interface MyClass : NSObject - (void)someInstanceMethod; // "-&qu...

Installation or Setup

Detailed instructions on getting ibm-midrange set up or installed.

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