In Java, 2D arrays are really arrays of arrays with possibly different lengths (there are no guarantees that in 2D arrays that the 2nd dimension arrays all be the same length)

You can get the length of any 2nd dimension array as `z[n].length` where `0 &lt;= n &lt; z.length`.  

If you&#39;re treating your 2D array as a matrix, you can simply get `z.length` and `z[0].length`, but note that you might be making an assumption that for each array in the 2nd dimension that the length is the same (for some programs this might be a reasonable assumption).

Expanding on what [Mark Elliot][1] said earlier, the easiest way to get the size of a 2D array given that each array in the array of arrays is of the same size is:

    array.length * array[0].length


  [1]: https://stackoverflow.com/a/4111400/3972558

Is there a function in C# that returns *x* times of a given char or string? Or must I code it myself?

Is there a built-in function to repeat a string or char in .NET?

What is the difference between DOM and HTML?

Difference between HTML and DOM

Okay, so I have a 2D array z[50][50] and z&#39;s size is therefore 50 * 50, but if I say z.length I only get 50 back. How do I get the real size of a 2D array?

Get the size of a 2D array

<p>Okay, so I have a 2D array z[50][50] and z's size is therefore 50 * 50, but if I say z.length I only get 50 back. How do I get the real size of a 2D array?</p>


Whenever I print something inside the servlet and call it by the webbrowser, it returns a new page containing that text. Is there a way to print the text in the current page using Ajax?

&lt;sub&gt;I&#39;m very new to web applications and servlets.&lt;/sub&gt;




How should I use servlets and Ajax?

How can i do this?

something:

    final View view=FLall.getChildAt(i);
    
    if (view.getType()==ImageView) {
    ...
    }



Android get type of a view

I&#39;m trying to use **eclipse** for **Java EE** to develop web applications. 

I need to use **Tomcat** as my **server**. I&#39;ve downloaded Tomcat and it&#39;s running. But my program doesn&#39;t compile. 

I get the following error: 
&gt;The import javax.servlet can&#39;t be resolved.

What do I need to do?

The import javax.servlet can&#39;t be resolved

Java for Mac OS X 10.6 Update 3 upgraded to java 1.6.0_22. However, they did not include the source code or JavaDoc. Does anyone know if Apple provides the source, and if so, where to find it?

I&#39;d like to attach the source to Eclipse.


Source code for Mac OS X Java Updates

I have a JPA entity with a property set as 

    @ManyToOne
    @Column(name=&quot;LicenseeFK&quot;)
    private Licensee licensee;

But when I deploy on JBoss 6 the application throws an error saying: 

    org.hibernate.AnnotationException: @Column(s) not allowed on a @ManyToOne property

I use Hibernate 3.5 as the JPA 2.0 implementation.

What should I use to reference the foreign key column?

@Column(s) not allowed on a @ManyToOne property

In C++ what is the difference (if any) between using char and char[1].

examples:

    struct SomeStruct
    {
       char x;
       char y[1];
    };


Do the same reasons follow for unsigned char?

Difference between char and char[1]

I use `in_array()` to check whether a value exists in an array like below,

    $a = array(&quot;Mac&quot;, &quot;NT&quot;, &quot;Irix&quot;, &quot;Linux&quot;);
    if (in_array(&quot;Irix&quot;, $a)) 
    {
        echo &quot;Got Irix&quot;;
    }
    
    //print_r($a);

but what about an multidimensional array (below) - how can I check that value whether it exists in the multi-array?

    $b = array(array(&quot;Mac&quot;, &quot;NT&quot;), array(&quot;Irix&quot;, &quot;Linux&quot;));
    
    print_r($b);

or I shouldn&#39;t be using `in_array()` when comes to the multidimensional array?

in_array() and multidimensional array

A [palindrome][1] is a word, phrase, number or other sequence of units that can be read the same way in either direction.

To check whether a word is a palindrome I get the char array of the word and compare the chars. I tested it and it seems to work. However I want to know if it is right or if there is something to improve. 

Here is my code:

    public class Aufg1 {
    	public static void main(String[] args) {
    		String wort = &quot;reliefpfpfeiller&quot;;
    		char[] warray = wort.toCharArray();	
    		System.out.println(istPalindrom(warray));		
    	}
    	
    	public static boolean istPalindrom(char[] wort){
    		boolean palindrom = false;
    		if(wort.length%2 == 0){
    			for(int i = 0; i &lt; wort.length/2-1; i++){
    				if(wort[i] != wort[wort.length-i-1]){
    					return false;
    				}else{
    					palindrom = true;
    				}
    			}
    		}else{
    			for(int i = 0; i &lt; (wort.length-1)/2-1; i++){
    				if(wort[i] != wort[wort.length-i-1]){
    					return false;
    				}else{
    					palindrom = true;
    				}
    			}
    		}
    		return palindrom;
    	}
    }


  [1]: http://en.wikipedia.org/wiki/Palindrome

Check string for palindrome

What are the advantages and disadvantages of each?

From what I&#39;ve seen, either one can work as a replacement for the other if need be, so should I bother using both or should I stick to just one of them?

Will the style of the program influence my choice? I am doing some machine learning using numpy, so there are indeed lots of matrices, but also lots of vectors (arrays).


What are the differences between numpy arrays and matrices? Which one should I use?

I have a JavaScript array `dataArray` which I want to push into a new array `newArray`. Except I don&#39;t want `newArray[0]` to be `dataArray`. I want to push in all the items into the new array:

    var newArray = [];

    newArray.pushValues(dataArray1);
    newArray.pushValues(dataArray2);
    // ...

or even better:

    var newArray = new Array (
       dataArray1.values(),
       dataArray2.values(),
       // ... where values() (or something equivalent) would push the individual values into the array, rather than the array itself
    );

So now the new array contains all the values of the individual data arrays.  Is there some shorthand like `pushValues` available so I don&#39;t have to iterate over each individual `dataArray`, adding the items one by one?

Copy array items into another array

I have an array defined:

    int [,] ary;
    // ...
    int nArea = ary.Length; // x*y or total area

This is all well and good, but I need to know how wide this array is in the `x` and `y` dimensions individually. Namely, `ary.Length` might return 12 - but does that mean the array is 4 high and 3 wide, or 6 high and 2 wide?

How can I retrieve this information?

How do you get the width and height of a multi-dimensional array?

When working with matrices in R, one can put them side-by-side or stack them top of each other using cbind and rbind, respectively. What is the equivalent function for stacking matrices or arrays in other dimensions?

For example, the following creates a pair of 2x2 matrices, each having 4 elements:

    x = cbind(1:2,3:4)
    y = cbind(5:6,7:8)

What is the code to combine them into a 2x2x2 array with 8 elements?


What is R&#39;s multidimensional equivalent of rbind and cbind?

There is the following query results: (key1 and key2 could be any text)

    id   key1     key2     value

    1    fred     apple    2
    2    mary     orange   10
    3    fred     banana   7
    4    fred     orange   4
    5    sarah    melon    5
    ...


and I wish to store the data in a grid (maybe as an array) **looping** all the records like this:

             apple    orange   banana  melon
    fred        2        4         7     -
    mary        -        10        -     -
    sarah       -        -         -     5


In PHP this would be really easy, using associative arrays:
    
    $result[&#39;fred&#39;][&#39;apple&#39;] = 2;

But in JavaScript associative arrays like this doesn&#39;t work.
After reading tons of tutorial, all I could get was this:

    arr=[];
    arr[1][&#39;apple&#39;] = 2;

but `arr[&#39;fred&#39;][&#39;apple&#39;] = 2;` doesn&#39;t work.
I tried arrays of objects, but objects properties can&#39;t be free text.
The more I was reading tutorials, the more I got confused...

Any idea is welcome :)

Multi-dimensional associative arrays in JavaScript

C++ inherited arrays from C where they are used virtually everywhere. C++ provides abstractions that are easier to use and less error-prone (`std::vector&lt;T&gt;` since C++98 and [`std::array&lt;T, n&gt;`](http://en.cppreference.com/w/cpp/container/array) since [C++11](https://en.wikipedia.org/wiki/C++11)), so the need for arrays does not arise quite as often as it does in C. However, when you read legacy code or interact with a library written in C, you should have a firm grasp on how arrays work.

This FAQ is split into five parts:

1. [arrays on the type level and accessing elements](https://stackoverflow.com/questions/4810668/)
2. [array creation and initialization](https://stackoverflow.com/questions/4984228/)
3. [assignment and parameter passing](https://stackoverflow.com/questions/4810672/)
4. [multidimensional arrays and arrays of pointers](https://stackoverflow.com/questions/4810676/)
5. [common pitfalls when using arrays](https://stackoverflow.com/questions/4810664/how-do-i-use-arrays-in-c/7439261#7439261)

If you feel something important is missing in this FAQ, write an answer and link it here as an additional part.

In the following text, &quot;array&quot; means &quot;C array&quot;, not the class template `std::array`. Basic knowledge of the C declarator syntax is assumed. Note that the manual usage of `new` and `delete` as demonstrated below is extremely dangerous in the face of exceptions, but that is the topic of [another FAQ](https://stackoverflow.com/questions/712639/).

&lt;hr&gt;

_(Note: This is meant to be an entry to [Stack Overflow&#39;s C++ FAQ](https://stackoverflow.com/questions/tagged/c++-faq). If you want to critique the idea of providing an FAQ in this form, then [the posting on meta that started all this](https://meta.stackexchange.com/questions/68647/setting-up-a-faq-for-the-c-tag) would be the place to do that. Answers to that question are monitored in the [C++ chatroom](https://chat.stackoverflow.com/rooms/10/c-lounge), where the FAQ idea started out in the first place, so your answer is very likely to get read by those who came up with the idea.)_

Content Type	Original Author	Original Content on Stackoverflow
Question	William	View Question on Stackoverflow
Solution 1 - Java	Mark Elliot	View Answer on Stackoverflow
Solution 2 - Java	Patrick Tyler	View Answer on Stackoverflow

Get the size of a 2D array

Java Problem Overview

Java Solutions

Solution 1 - Java

Solution 2 - Java

Difference between HTML and DOM

Is there a built-in function to repeat a string or char in .NET?

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