Programming Languages-Other

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A programming language is a formal constructed language designed to communicate instructions to a machine, particularly a computer. Thousands of different programming languages have been created, mainly in the computer field, and many more still are being created every year. The description of a programming language is usually split into the two components of syntax (form) and semantics (meaning). Some languages are defined by a specification document (for example, the C programming language is specified by an ISO Standard), while other languages (such as Perl) have a dominant implementation that is treated as a reference. Some languages have both, with the basic language defined by a standard and extensions taken from the dominant implementation being common.

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Hi Experts

Could you point a way to join multiple .CSV(s) files into one?

I had tried  to use TXTCollector but it doesn't work fine everytime.

Sometimes this error occurs:
[Error] - File could not be written...

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Amazingly the files were generated the same way.

Thanks in advance!
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Expert Spotlight: Joe Anderson (DatabaseMX)
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Expert Spotlight: Joe Anderson (DatabaseMX)

We’ve posted a new Expert Spotlight!  Joe Anderson (DatabaseMX) has been on Experts Exchange since 2006. Learn more about this database architect, guitar aficionado, and Microsoft MVP.

how to understand big new project code quickly and effectively to write new enhancement to existing code or to fix some defects or to debug to improve some areas of poor performance.

what are the tips and recommendations , best practices around this
Please advise
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what is difference between below two eclipse short cuts

control +alt+h
(above does not yield any results saying members calling that method in workspace it shows at bottom again same method nothing else)

control +shift+g
(above shows like 8 references in workspace)

please advise
shortcut.png
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I've been looking into other languages and was wondering which one is the best for locking down and protecting your source code.

Is it even possible to encrypt/lock your source code in any language?

I don't want to learn a language, invest years of time developing something, then have someone immediately copy my source and sell a derivative before I can turn a profit on it.
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HI,
Is there any website where one can post there understanding of computer science concepts or explain them and then user can ask questions. Although expert exchange also has article section.
But i want to specifically do it for Java concepts Java 8 features etc.
The idea is to feel motivated to study it... as it helps learning the material in a quicker way
Any alternative suggestions
Thanks
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lets say i have method called
 testSum(){
c=a+b;
}

i clicked on testSum
i did CONTROL+ALT+H i see call hierarchy results
if I clicked testSum did CONTROL+H  then i get search option with my method and its class, package selected automatically and i click SEARCH without changing anything(it says java search)

how above call hierarchy different from java search is different from previous one?

please advise
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Hi, I'm documenting a change in a web page (not written by my company)and encountered the following snippet. What language is it? JavaScript? Thanks.

(function() { function forEach(responses, cb) { Object.keys(responses).forEach(function(adUnitCode) { var response = responses[adUnitCode]; response.bids.forEach(function(bid) { cb(adUnitCode, bid); }); }); } var winners = pbjs.getAllWinningBids(); var output = []; forEach(pbjs.getBidResponses(), function(code, bid) { output.push({ bid: bid, adunit: code, adId: bid.adId, bidder: bid.bidder, time: bid.timeToRespond, cpm: bid.cpm, msg: bid.statusMessage, rendered: !!winners.find(function(winner) { return winner.adId==bid.adId; }) }); }); forEach(pbjs.getNoBids && pbjs.getNoBids() || {}, function(code, bid) { output.push({ msg: "no bid", adunit: code, adId: bid.bidId, bidder: bid.bidder }); }); if (output.length) { if (console.table) { console.table(output); } else { for (var j = 0; j < output.length; j++) { console.log(output[j]); } } } else { console.warn('NO prebid responses'); } })(); 

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I've inherited some 10+ year old code without benefit of the original programmer... can anyone explain the usefulness of this code segment, or at least reduce to something more sensible?

                                                       Display Module Source                                                        
                                                                                                                                   
C  N31USERN         CABNE     *ALL' '                            3131--                                  

Thanks in advance ;)
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I writing python program which read specific text from text file.

The program is working fine if it is static line index.

if it is dynamic search in the whole document, i am unable to read..

particularly, i want to get "Join Date","Relieve Date",etc. along with 3 main parameter(EmpNo,Name,Salary).

How to change the below code..?

Code attached in the below link

Sample TXT File https://1drv.ms/t/s!AiSRcgO5FUmNeTflVF53ZBkuv8Y
TEST_StackOverflow.txt
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Become a CompTIA Certified Healthcare IT Tech
LVL 13
Become a CompTIA Certified Healthcare IT Tech

This course will help prep you to earn the CompTIA Healthcare IT Technician certification showing that you have the knowledge and skills needed to succeed in installing, managing, and troubleshooting IT systems in medical and clinical settings.

try{
			
			previouslyTaken = new DataDAO().testForPkgPreviouslyTaken(this....., TimeStamp);//gives true or false boolean value
		}
		catch (XYZExceptionException xyze)
		{
			if(xyze.getMessage().contains("999"))
			{
				LOGGER.error("item is PreviouslyTaken due to aa", xyze);
				errorCodes.add(XYZConstants.PREVIOUS_TAKEN_EXISTS);				
			}
			else if(xyze.getMessage().contains("888"))
			{
				LOGGER.error("item is PreviouslyDumped due to bb", xyze);
				errorCodes.add(XYZConstants.PREVIOUSLY_DUMPED);
			}
			else
			{
				throw new XYZException(xyze);
			}	
			return ;
		}
		LOGGER.info("previouslyTaken indicator from DB {}",previouslyTaken); //coming false t me
		
		if(!previouslyTaken){
		processIt();
		else
		LOGGER.info("item taken or dumped so update status to new)

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i have above code in a method.

i never saw if else inside a catch in earlier.

why some one use if else inside catch
when the catch is thrown as try block simply return true or false

when it has 999 or 888 etc value in the xyze exception

please advise
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MQ under glassfish called imqdbroker not running when i double click on windows laptop.
path is
C:\Program Files\glassfish-4.0\mq\bin
i am not able to open default hosts under jms host to see that same mq that is supposed to be started
Please advise
MQ_glasfish.png
MQ_glasfish_2.png
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hi,

I build one stateless session bean example with presentation tier html inddex page and web tier servlet within ejb web project then business tier in the ejb project


<!DOCTYPE html>
<!--
To change this license header, choose License Headers in Project Properties.
To change this template file, choose Tools | Templates
and open the template in the editor.
-->
<html>
    <head>
        <title>TODO supply a title</title>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
    </head>
    <body>
        <form action="ConverterServlet" method="POST">
              <input type="number" name="value"></br>
              <select name="type">
                    <option value="C2F">celcius to fahrenheit</option>
                    <option value="F2C">fahrenheit  to celcius</option>
              </select></br>
              <input type="submit" value="Convert">
        </form>
            
    </body>
</html>

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do i not need to add close tags for input html element
<input type="submit" value="Convert">

also do i not need to ad begin tag for </br>

please advise

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package servlet;

import bean.ConverterBeanLocal;
import bean.ConverterBeanLocal.ConvertType;
import java.io.IOException;
import java.io.PrintWriter;

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one registerPhone flow goes through 30 stored procedures. Each stored proc connecting database individually and taking 100 milli seconds to connect.

so 30 multipled by 100 total 3000 milli seconds wasted due to this.

can i make all 30 stored procedures into one call so that only one database connection happens for 100 milli seconds

Like to save those 3000 milli seconds when i can do only with 100 milli seconds

Please advise
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How do i read particular text (like empno, name, salary,etc) from text file and store those values in SQL table using python.

I am new for python and i want sample code this ASAP.
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Hi Experts

Could you point what must to be done to make a PowerBuilder 6.5 project to be used on PowerBuilder 7.0?

I saw that "workspace"  must to be used but how to make the old  libraries to enter on it...


Thanks in advance!
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Constructors are not inherited:
The sub class cannot inherit constructors from its super class. Consider the following example:
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public class Super {
    protected String text;
 
    public Super(String text) {
        this.text = text;
    }
}
 
public class Sub extends Super {
 
}
We can create a new instance of Super like this:
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Super super = new Super(“Hello”);   //OK
But we cannot do the same for the Sub class:
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Sub sub = new Sub(“Hello”); //Compile error, since constructor is not inherited
The solution is to write a constructor for the sub class and call the super’s constructor, for example:
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public class Sub extends Super {
 
    public Sub(String text) {
        super(text);
    }
}

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https://www.codejava.net/java-core/the-java-language/12-rules-and-examples-about-inheritance-in-java

i wrote as below

package SuperSub;
public class Super {
    protected String text;
 
    public Super(String text) {
        this.text = text;
    }
}
 

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package SuperSub;
public class Sub extends Super {
	//Super super = new Super(“Hello”);
}

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i am getting error in line 2 of Sub class
Implicit super constructor Super() is undefined for default constructor. Must define an explicit constructor
package SuperSub;
public class Sub extends Super {

	public Sub(String text) {
		super(text);
		// TODO Auto-generated constructor stub
	}
	//Super super = new Super(“Hello”);
}

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above is fine though not sure why i cannot just have Sub empty class?
Please advise
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package SuperThis;
public class Sub extends Super {
	/*public static void main(String[] args) {
		  super.bar();
	      this.bar();
	}*/
    public void bar() {
        System.out.println("Sub.bar()...");
    }
 
 
    public void test() {
       super.bar();
       this.bar();
    }
  
    	// Sub sub=new Sub();
    	 //   sub.test();
    
        this.test();
}

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why above code is not working
i see error as below at line 21,15
Syntax error, insert "}" to complete ClassBody

Please advise
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The super keyword:
In Java, the superkeyword is used to access members of the super type from the sub type. For example:
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public class Super {
    protected void bar() {
        System.out.println("Super.bar()...");
    }
 
}
 
public class Sub extends Super {
    public void bar() {
        System.out.println("Sub.bar()...");
    }
 
 
    public void test() {
        super.bar();
        this.bar();
    }
}
Here, we can see that both classes have a method called bar() (overriding). Therefore, if we want to invoke the super’s version of the bar() method, the super keyword is used.
 

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super with this example not working for me
package SuperThis;
public class Sub extends Super {
	public static void main(String[] args) {
		  super.bar();
	      this.bar();
	}
    public void bar() {
        System.out.println("Sub.bar()...");
    }
 
 
    //public void test() {
       // super.bar();
        //this.bar();
   // }
        
}

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above code giving below error
Cannot use super in a static context
Cannot use this in a static context

how to fix this
package SuperThis;

public class Test {
public static void main(String[] args) {
	 Sub sub=new Sub();
	    sub.test();
}
}

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Super.bar()...
Sub.bar()...


does it need separate class for this to test
package SuperThis;
public class Sub extends Super {
	/*public static void main(String[] args) {
		  super.bar();
	      this.bar();
	}*/
    public void bar() {
        System.out.println("Sub.bar()...");
    }
 
 
    public void test() {
       super.bar();
       this.bar();
    }
  
    	// Sub sub=new Sub();
    	 //   sub.test();
    
        test();
}

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how to test in same Sub class

above gives error at line 20
Multiple markers at this line
      - This method requires a body instead of a
       semicolon
      - Return type for the method is missing
      - Duplicate method test() in type Sub

please advise
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Introduction to Web Design
LVL 13
Introduction to Web Design

Develop a strong foundation and understanding of web design by learning HTML, CSS, and additional tools to help you develop your own website.

One interesting point with inheritance in Java is that, we can use the super type when creating a new object of the sub type.
Suppose Car is the parent class of the Truck class as shown in the following code:
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public class Car {
    public void move() {
    }
}
 
public class Truck extends Car {
    public void load() {
    }
}
It’s legal to write:
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Car vehicle = new Truck();
The rule is: the type on the left side can be super type of the actual object in the right side. Note that the only methods we can invoke are the ones declared in the super type, for example:
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vehicle.move(); //okay, since Truck inherits Car
Also note that, if the subclass declares a new method, we cannot invoke it using the super type reference:
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vehicle.load(); // compile error

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IF i take parent type and object as child i am getting error.

but when i cast it as below no error

can you please advise why no error

package ParentSuperTypeObjectSubType;

public class TestClass {
	public static void main(String[] args) {
		Car vehicle = new Truck();
		vehicle.move(); //okay, since Truck inherits Car
		vehicle.load(); // compile error
		((Truck) vehicle).load(); // ok
	}

}

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below also worked fine if i cast
package ParentSuperTypeObjectSubType;

public class TestClass {
      public static void main(String[] args) {
            Car vehicle = new Truck();
            Truck car = new Car();  // Compile error
            Truck car = (Truck) new Car();  // Compile error
            vehicle.move(); //okay, since Truck inherits Car
            vehicle.load(); // compile error
            ((Truck) vehicle).load(); // ok
      }

}



is above is upcast or downcast
i confuse those similar name?
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Remember that Java does not allow a class inherits two or more classes directly. To understand why multiple inheritance is not allowed, consider the following example:
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public class A {
    public void methodA() {
 
    }
 
    public void foo() {
 
    }
}
 
 
public class B {
    public void methodB() {
 
    }
 
    public void foo() {
 
    }
}
Suppose that we want to write a class C that extends both A and B like this:
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public class C extends A, B {
    public void methodC() {
        foo();
    }
}
As you can see, both A and B has a method called foo(), so which foo() method the class C invokes exactly? from A or B? This case is ambiguous hence Java does not allow.

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https://www.codejava.net/java-core/the-java-language/12-rules-and-examples-about-inheritance-in-java

i tried as below

package MultipleInheritance;
public class A {
    public void methodA() {
 
    }
 
    public void foo() {
 
    }
}


package MultipleInheritance;
public class B {
    public void methodB() {
 
    }
 
    public void foo() {
 
    }
}


package MultipleInheritance;
public class C extends A, B {
    public void methodC() {
        foo();
    }
}

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on C class i get below error

Multiple markers at this line
      - Syntax error on token "extends", delete this token
      - Syntax error, insert "ClassBody" to complete
       ClassDeclaration
      - Syntax error, insert "}" to complete Block

can you please advise what above error means

it did not say "multiple inheritance of state not allowed"

Please advise
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6. Multiple inheritance of state is not allowed:
Remember that Java does not allow a class inherits two or more classes directly. To understand why multiple inheritance is not allowed, consider the following example:
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public class A {
    public void methodA() {
 
    }
 
    public void foo() {
 
    }
}
 
 
public class B {
    public void methodB() {
 
    }
 
    public void foo() {
 
    }
}
Suppose that we want to write a class C that extends both A and B like this:
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public class C extends A, B {
    public void methodC() {
        foo();
    }
}
As you can see, both A and B has a method called foo(), so which foo() method the class C invokes exactly? from A or B? This case is ambiguous hence Java does not allow.
 
7. Multiple inheritance of type is allowed:
This means Java does allow multiple inheritance between interfaces. For example:
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public interface X {
    public void methodX();
}
 
public interface Y {
    public void methodY();
}
 
public interface Z extends X, Y {
    public void methodZ();
}
This is allowed because interfaces do not have concrete methods, thus there is no ambiguity.
Likewise, we can have a class implements multiple interfaces:
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public class Sub implements X, Y, Z {
    public void methodX() { }
 
    public void methodY() { }
 
    public void methodZ() { }
}

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if both Interface X and Interface Y has same method called methodAB what happens?



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Let’s look at the constructor of the Truckclass - it can access the protected field numberOfWheels and the default field name. However, it cannot access the private field age. We can write:
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Truck truck = new Truck();
truck.start();
truck.move();
But the Java compiler will complain if we try to invoke the private method test():
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truck.test();   // COMPILE ERROR, since private member is not inherited

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https://www.codejava.net/java-core/the-java-language/12-rules-and-examples-about-inheritance-in-java


i supposed to put below code in which class Car or Truck or Moveable?


public class Truck extends Car {
    public Truck() {
        numberOfWheels = 8;
        name = "Truck";
        age=10;
    }
    
    Truck truck = new Truck();
    truck.start();
    truck.move();
    
}

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or as below

public class Car extends Vehicle {
	String name;
	protected int age;
    //protected int age;
    protected int numberOfWheels = 4;
    
    public void move() {
        System.out.print("Moving by engine...");
    }

	@Override
	public void start() {
		// TODO Auto-generated method stub
		
	}

	@Override
	public void stop() {
		// TODO Auto-generated method stub
		
	}
	
	/*Truck truck = new Truck();
	truck.start();
	truck.move();*/
}

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below i cannot put as it is interface

public interface Moveable {
    public void start();
 
    public void stop();
 
    public void move();
}

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please advise
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Don’t use a for loop with an index (or counter) variable if you can replace it with the enhanced for loop (since Java 5) or forEach (since Java 8). It’s because the index variable is error-prone, as we may alter it incidentally in the loop’s body, or we may starts the index from 1 instead of 0.
Consider the following example that iterates over an array of Strings:
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String[] names = {"Alice", "Bob", "Carol", "David", "Eric", "Frank"};
 
for (int i = 0; i < names.length; i++) {
    doSomething(names[i]);
}
As you can see, the index variable i in this for loop can be altered incidentally which may cause unexpected result. We can avoid potential problems by using an enhanced for loop like this:
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for (String aName : names) {
    doSomething(aName);
}
This does not only remove potential issues but also make the code cleaner and more succinct. 

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how is it possible to do for loop index modifycation?

how enhanced for loop is diferent from for each loop?

is there any case where we still has to use traditional for loop with index
please advise
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public class CollectionsRef {
 
    private HashSet<Integer> numbers;
 
    public ArrayList<String> getList() {
 
        return new ArrayList<String>();
    }
 
    public void setNumbers(HashSet<Integer> numbers) {
        this.numbers = numbers;
    }
}
Look at the reference types which are collection implementation classes - this locks the code to work with only these classes HashSet and ArrayList. What if we want the method getList() can return a LinkedList and the method setNumbers() can accept a TreeSet?
The above class can be improved by replace the class references to interface references like this:
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public class CollectionsRef {
 
    private Set<Integer> numbers;
 
    public List<String> getList() {
        // can return any kind of List
     [b]   return new ArrayList<String>();[/b]
    }
 
    public void setNumbers(Set<Integer> numbers) {
        // can accept any kind of Set
        this.numbers = numbers;
    }
}

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can we have generic List as return type to provide more flexibility to future changes to collection implementation?
https://www.codejava.net/coding/10-java-core-best-practices-every-java-programmer-should-know
Please advise
0

Programming Languages-Other

19K

Solutions

19K

Contributors

A programming language is a formal constructed language designed to communicate instructions to a machine, particularly a computer. Thousands of different programming languages have been created, mainly in the computer field, and many more still are being created every year. The description of a programming language is usually split into the two components of syntax (form) and semantics (meaning). Some languages are defined by a specification document (for example, the C programming language is specified by an ISO Standard), while other languages (such as Perl) have a dominant implementation that is treated as a reference. Some languages have both, with the basic language defined by a standard and extensions taken from the dominant implementation being common.