General

It has been a long time since the last major release of PHP, which is one of the most widely used languages in the world.

PHP 5.6 was released in 2005.About eleven years after that latest version of PHP was released in Dec 2015.As expected PHP 7.0
includes many improvements over the previous version.

The features provided by PHP 7.0 can be categorized into two main categories

Performance

PHPNG

If you have been using PHP since long then you will be happy to know that PHP 7 is nearly twice as fast as PHP 5.6.This is demonstrated by testing some major PHP projects such as WordPress and Drupal.
The main reason for improved performance of PHP 7 is the new version of Zend Engine ,Zend Engine 3. Zend Engine is an execution engine which is responsible for interpreting and executing PHP code. With Zend Engine 3 PHP applications run 2 X as fast as compared to the previous version of PHP. Zend engine 3 is also code named phpng.

Removal of Deprecated APIs

Many APIs were deprecated in PHP5.x.So most likely you might not be using these APIs.So to make PHP optimal these deprecated have been removed in PHP 7.Some of these are:

aolserver
apache
apache_hooks
caudium

Language Enhancements

Scalar type hints
As we know sometimes its good if a variable is assigned to a particular type to prevent unexpected errors from happening.
With the previous version of PHP we could specify the type of function arguments.

With Scalar type hints in PHP 7 we can also declare variables of scalar types.Scalar types are int, float, string, and bool.

function Add(float $a, float $b) {
return $a + $b;
}

Return Type Declarations
Return type declaration ensures that the function returns the correct type.For example a function expected to return int should not return string.

To enable type checking using Return type declaration we should enable strict type checking as:

declare(strict_types=1);

Now if we declare the function as:

function Add(int $a, int $b) : int {
return $a + $b;
}

and try to call

Add("a", "b");

we will get fatal error

Handling Fatal Errors
In PHP 5.6 when a fatal error occurs we can not catch it.So we have no other option to the default white screen being shown to the user.There was no support to catch Fatal errors.In PHP 7.0 we can catch the Fatal errors.We can catch Fatal errors using the EngineException class type.If the Fatal error is not caught then it will behave in a similar way to PHP 5.6 ,resulting Fatal error and blank screen shown to the user.

Spaceship operator

<=> is called the spaceship operator.This operator makes it easier to write comparison expressions.
$a<=>$b will return the following
1 if $a is greater than $b
0 if both are equal
-1 if $b is greater than $a

Null coalescing operator
This operator is denoted by ??.It makes it easier to check if variable is assigned a value.It is a good alternative to ternary ?x:y operator in many cases.Below are the two different ways of writing the same comparison expression in PHP 5.6 and PHP 7.0.You can see that the first expression is much easier to understand.

//PHP 7.0 ?? operator
$loginId=$_GET['loginId']??'Empty';

//PHP 5.6 ternary operator
$loginId=isset($_GET['loginId'])?$_GET['loginId']:'Empty';

Anonymous class

Anonymous class is a class which does not have a name.Anonymous class is a feature of other object oriented languages such as C# and Java.

You use anonymous class when you need a class only once.Anonymous class is defined as:

$obj = new class 
extends A{

public function Print()
{

}

};

As can be seen there is a difference between how we instantiate object of anonymous class.In the case of anonymous class there is no name.Instead new operator is followed by the class definition.

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For string comparison in two of the useful methods are:

equals() method

String class overrides the equals() method of the object class.The overriden method compares the contents of one string with another to check for equality.

The following method compares the two strings using the equals method.

public static void main(String []args) throws IOException {

String string1 = new String("java string");
String string2 = new String("java string");
String string3 = new String("hello");
boolean boolean1, boolean2,boolean3;
boolean1 = string1.equals(string2); // false will be assigned to b1
boolean2 = string1.equals(string3);
System.out.println(boolean1);
System.out.println(boolean2);
}

Above code prints the following values
true
false

comapreTo() method

compareTo method is used for comparing two strings for equality.It is used as:

int retrunValue=string1.compareTo(string2)

retrunValue is 0 if the two strings are equal.
retrunValue is >1 if string1 is greater than string2
retrunValue is <1 if string1 is less than string2

Following example program compares strings for equality

public static void main(String []args) throws IOException {

String string1 = new String("java string");
String string2 = new String("java string");
String string3 = new String("hello");

int areEqual1="java string".compareTo("java string");
int areEqual2="java string".compareTo("hello");
System.out.println(areEqual1);
System.out.println(areEqual2);
}

Above code prints the following values

0
2

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Applications are getting more responsive and user friendly these days.This means that the user should always be kept informed about the status of the application and application should be fast and not get stuck in some long running operation.

Also hardware is getting more powerful day by day.These days it is not unusual to have CPUs having multiple cores.
Normally method execution is synchronous.So if we have 2 method calls as:

void Main()
{
method1()
method2()

}

So method1 will execute and after it finishes execution then method2 will execute.

To allow the application to work even when a long running process is executing it needs to be asynchronous.This means that the long running process should not block the main UI thread and should rather get executed on a separate thread.To achieve this asynchronous functionality should be implemented in the application.

Some of the ways to implement asynchronous code are:

• Threads
• Tasks
• async and await keywords

Previously implementing asynchronous code in a application was a complex process.But now with the async and await keywords in c# we can easily implement applications which remains responsive even when waiting for a long running process to complete.

To implement asynchronous operation we can follow the below steps:

1.declare a long running method using the async keyword.This method should return either Task,Task<T> or void

Below we have declared a method called GetResultsAsync

private async Task GetResultsAsync()
{

}

2. Call the long running operation from within the method using await keyword

Call the method you want to call asynchronously and mark it with the keyword await.In the following method we have called the method FetchById asynchronously by marking it with the keyword await.

At the point in execution when await keyword is encountered the execution returns to the calling method.And when the awaited method finishes execution control returns back to the the point where we call the awaited method.
Its important to remember that we can call only those method asynchronously which returns Task<T> or Task.

private static async Task<int> GetResultsAsync()
{
//perform operations 
int a = 2;
int b = 1;
int c = a + b;

WebClient client = new WebClient();
var result = await FetchById();
Console.WriteLine("This is printed from asynchronous method {0}",result);
return result;

}

3.Implement the method which implements the long running task

Declare the long running method which you need to execute asynchronously.Below we have declared the method FetchById() asynchronously.
Though most of the times the method will implement code which takes really long to execute.Also this method should return Task<T> where T is the data type which needs to be returned to the calling method.

public static Task<int> FetchById()
{
var coll1 =new string[] { "a", "b", "c", "d" };
return Task.Run<int>(() =>1 );
}

We get the following output after the above code executes

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When we think about big data the thought which comes immediately to mind is huge amount of data.This description of big data might be true but big data is recognized by other characteristics as well apart from just huge amount of data.
To understand what is big data it is helpful to first think about the need of big data.After all database management systems and data warehouses can handle huge amounts of data.

Data is getting generated at an ever increasing rate.90% of data today is generated over the last two years.This can give us some idea about the rate at which the data is being generated.And its not just the amount of data which is increasing.The types of data which is getting generated is also
disparate.
Some of the different types of data being generated today are:

• Social media data from social networking sites such as twitter,google
• Databases From systems such as enterprise applications
• XML and JSON  From web services and applications
• Raw data From systems such as mobile sensors

Images,Video and Audio From systems such as enterprise applications and social networking sites

So we can understand that two of the main characteristics of the data is getting generated today and the data that will be generated in future will have these two characteristics:

• Huge volume of data
• Different types of data
• Apart from these two there is one more attribute that is common of this data being generated ,which is velocity.Velocity means the speed at which the data is getting generated.

So the characteristics which describes big data are

• Volume Huge amount of data ,that is data in terabytes or petabytes
• Variety Different types of data ,such as structured,semi structured and unstructured ,e.g ,relational data,video,audio,emails.
• Velocity High rate at which data is generated and processed.

The above are also called the three V’s of big data.These define a data source as big data.

Is simple words we can say that big data are enormously large data sets that traditional data processing applications are not capable of processing.
The main challenges offered by such data sets are

• Storage
• Processing
• Analysis

Analyzing big data can provide benefits such as predicting the future outcome by revealing the patterns in the existing data.Some areas are:

• Predicting the challenges which an organization can face
• Diagnosing the diseases which could occur in a particular geography
• Predicting the buying behaviors of customers based on their past history.

Big data analytics provide better,timely and accurate decision making for an organization.

There are few different technologies and techniques which allows to handle the big data.There are technologies from vendors such as Oracle,Microsoft.But the most widely used used is Apache Hadoop.It is an open source project developed by Doug Cutting.

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