The question is just playing with you with confusing spacing.

`b != b` is the usual `!=` (not equals) comparison.

On the other hand:

`b =! b` is better written as `b = !b` which is parsed as:

    b = (!b)

Thus it&#39;s two operators.

 1. First invert `b`.
 2. Then assign it back to `b`.

The assignment operator returns the assigned value. Therefore, `(b =! b)` evaluates to true - which is what you print out.

`b != b` means `! (b == b)`: the opposite of `b == b`.

`b =! b` is actually `b = !b`, an assignment. It&#39;s toggling `b`&#39;s value. An assignment evaluates to the value of the expression, so this will evaluate to `!b` (along with having changed the value of `b`).

`b=!b` is an assignment. It assigns `b` to `!b` and the expression evaluates to the resulting value, which is `true`.

b =! b

you are doing an assignment, you are saying that B should have the value of !B. 

b != b


You are asking if B is different than b



**UPDATE**

Here are the constraints as a result of the query

    SELECT * FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE TABLE_NAME = &#39;history&#39;

    CONSTRAINT_NAME   COLUMN_NAME  ORDINAL_POSITION
    PK_history        userKey       1
    PK_history        name          2

Here is the result of the query
    
    SELECT * 
    FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS 
    WHERE TABLE_NAME = &#39;history&#39;

    CONSTRAINT_NAME   CONSTRAINT_TYPE  IS_DEFERRABLE  INITIALLY_DEFERRED
    PK_history        PRIMARY KEY      NO             NO

**END UPDATE**

My host provides an interface to my SQL Server DB via ASP.NET Enterprise Manager.  

I have 3 columns in my `history` table: 

- `userId` (key, int, NULL not allowed)
- `name` (key, string, NULL not allowed)
- `id` (not key, int, NULL allowed)

I want to make the id column the only key.

To do that, I believe I need to:

 1. Make sure there are no NULLs in that column for any row
 2. Set the column to not allow NULLs
 3. Add the column as a primary key
 4. Remove the other 2 columns as keys

However, when I use the UI provided, it never works. Sometimes it&#39;ll just look like it tries to do something but it never changes when I refresh the view of the columns. It occasionally creates a temp table that looks like it tried to do some of the operation, but that never gets copied/overwrites the original table that I&#39;m trying to change.

When I try using a query, the changes don&#39;t show up either. Here are the queries I think I need:

        SELECT * from history WHERE id is NULL     &lt;---- This shows 0 results

        ALTER TABLE history
        ALTER COLUMN id int NOT NULL

        ALTER TABLE history ADD PRIMARY KEY (id)

        ALTER TABLE history
        DROP CONSTRAINT userId
        DROP CONSTRAINT name
        GO

I&#39;ve only gotten to the attempt to disallow NULLs and to add the primary key for the id column. It doesn&#39;t seem to work. Can someone point me in the right direction? Thanks!



Change primary key column in SQL Server

I&#39;m searching for a better solution to making an AJAX call with jQuery, having the PHP file return an array, and have it come out client-side as a Javascript array. Here is what I have been doing this:

PHP File (Example.php):  

    &lt;?php
        $id_numbers = array(&#39;NES-ZL&#39;,&#39;NES-AL&#39;,&#39;SNS-ZL&#39;);
        
        for ($i=0; $i&lt;count($the_array); $i++){
            echo $id_numbers[$i];
            echo &#39;|&#39;;
        }
    ?&gt;

JS File:  

    id_numbers = new Array();
    $.ajax({
        url:&quot;Example.php&quot;,
        type:&quot;POST&quot;,
        success:function(msg){
            id_numbers = msg.split(&#39;|&#39;);
        }
    });

My current method is just a little too convoluted for my taste.

What I&#39;d like to do is to be able to just

    return $id_numbers;

on the PHP side and directly translate it to a Javascript array after the AJAX call.

Ideas, anyone?

How to return an array from an AJAX call?

I was looking over some mock [OCJP][1] questions. I came across a really baffling syntax. Here it is:

    class OddStuff {
    	public static void main(String[] args) {
            boolean b = false;
            System.out.println((b != b));// False
            System.out.println((b =! b));// True
        }
    }

Why does the output change between `!=` and `=!`?

  [1]: https://en.wikipedia.org/wiki/Oracle_Certification_Program


What is the difference between != and =! in Java?

I was looking over some mock <a href="https://en.wikipedia.org/wiki/Oracle_Certification_Program" target="_blank" rel="noopener noreferrer">OCJP</a> questions. I came across a really baffling syntax. Here it is:
<pre><code class="hljs language-typescript">class OddStuff {
	public static void main(String[] args) {
 boolean b = false;
 System.out.println((b != b));// False
 System.out.println((b =! b));// True
 }
}
</code></pre>
Why does the output change between <code>!=</code> and <code>=!</code>?

On this Oracle page [Java HotSpot VM Options][1], it lists `-XX:+UseCompressedStrings` as being available and on by default.  However in Java 6 update 29, it is off by default and in Java 7 update 2 it reports a warning

    Java HotSpot(TM) 64-Bit Server VM warning: ignoring option UseCompressedStrings; support was removed in 7.0

Does anyone know the thinking behind removing this option?

---

https://stackoverflow.com/questions/8832822/sorting-lines-of-an-enormous-file-txt-in-java/8833257#8833257 

With `-mx2g`, this example took 4.541 seconds with the option on and 5.206 second with it off in Java 6 update 29. It is hard to see that it impacts performance.

Note: Java 7 update 2 requires 2.0 G whereas Java 6 update 29 without compressed strings requires 1.8 GB and with compressed string requires only 1.0 GB.


  [1]: http://www.oracle.com/technetwork/java/javase/tech/vmoptions-jsp-140102.html

Support for Compressed Strings being Dropped in HotSpot JVM?

I have a Java date object:

    Date currentDate = new Date();

This will give the current date and time. Example:

    Thu Jan 12 10:17:47 GMT 2012

Instead, I want to get the date, changing it to one hour back so it should give me:

    Thu Jan 12 09:17:47 GMT 2012

What would be the best way to do it?

Changing Java Date one hour back

Here is my code.  For some reason my BMI is not calculated correctly.
When I check the output on a calculator for this : `(10/((10/100)^2)))` I get 1000, but in my program, I get 5.  I&#39;m not sure what I am doing wrong.  Here is my code:


    import javax.swing.*;

    public class BMI {
        public static void main(String args[]) {
            int height;
            int weight;
            String getweight;
            getweight = JOptionPane.showInputDialog(null, &quot;Please enter your weight in Kilograms&quot;);
            String getheight;
            getheight = JOptionPane.showInputDialog(null, &quot;Please enter your height in Centimeters&quot;);
            weight = Integer.parseInt(getweight);
            height = Integer.parseInt(getheight);
            double bmi;
            bmi = (weight/((height/100)^2));
            JOptionPane.showMessageDialog(null, &quot;Your BMI is: &quot; + bmi);
        }
    }


Raising a number to a power in Java

I don&#39;t understand what exactly [Camel](http://camel.apache.org/index.html) does.

If you could give in 101 words an introduction to Camel:

* What exactly is it? 
* How does it interact with an application written in Java? 
* Is it something that goes together with the server? 
* Is it an independent program? 

**Please explain what Camel is.**

What exactly is Apache Camel?

I have worked in a SOAP message to get the LoginToken from a Webservice, and store that LoginToken as a String. U used `System.out.println(LoginToken);` to print the value. This prints `[wdsd34svdf]`, but I want only `wdsd34svdf`. How can I remove these square brackets at the start and end of the output?

Example:

    String LoginToken=getName().toString();
    System.out.println(&quot;LoginToken&quot; + LoginToken);

The output is: `[wdsd34svdf]`.

I want just `wdsd34svdf`

How to remove the first and last character of a string?

What is the meaning of a bash variable used like this:

     ${Server?}



What is the meaning of a question mark in bash variable parameter expansion as in ${var?}?

Given a 3 times 3 numpy array

    a = numpy.arange(0,27,3).reshape(3,3)

    # array([[ 0,  3,  6],
    #        [ 9, 12, 15],
    #        [18, 21, 24]])


To normalize the rows of the 2-dimensional array I thought of

    row_sums = a.sum(axis=1) # array([ 9, 36, 63])
    new_matrix = numpy.zeros((3,3))
    for i, (row, row_sum) in enumerate(zip(a, row_sums)):
        new_matrix[i,:] = row / row_sum

There must be a better way, isn&#39;t there?

Perhaps to clearify: By normalizing I mean, the sum of the entrys per row must be one. But I think that will be clear to most people.

How to normalize a 2-dimensional numpy array in python less verbose?

&gt; **Possible Duplicate:** &lt;br/&gt;
&gt; [What is the (function() { } )() construct in JavaScript?](https://stackoverflow.com/questions/8228281/what-is-this-construct-in-javascript)

&lt;!-- End of automatically inserted text --&gt;

I came across this bit of JavaScript code, but I have no idea what to make out of it. Why do I get &quot;1&quot; when I run this code? What is this strange little appendix of (1) and why is the function wrapped in parentheses?

    (function(x){
        delete x;
        return x;
    })(1);


Advanced JavaScript: Why is this function wrapped in parentheses?

I was thinking if there exists a better/nicer way to negate an `instanceof` in Java.
Actually, I&#39;m doing something like:

    if(!(myObject instanceof SomeClass)) { /* do Something */ }

But I think that a &quot;beautiful&quot; syntax to do this should exist.


Does anyone know if it exists, and how the syntax look like?


----------


**EDIT:**
By beautiful, I might say something like this:

    if(myObject !instanceof SomeClass) { /* do Something */ } // compilation fails


Best way to &quot;negate&quot; an instanceof

Block syntax in Objective C (and indeed C, I presume) is notoriously incongruous. Passing blocks as arguments looks different than declaring blocks as ivars, which looks different than `typedef`ing blocks.

Is there a comprehensive list of block-declaration syntax that I could keep on hand for quick reference?

Content Type	Original Author	Original Content on Stackoverflow
Question	prometheuspk	View Question on Stackoverflow
Solution 1 - Java	Mysticial	View Answer on Stackoverflow
Solution 2 - Java	Claudiu	View Answer on Stackoverflow
Solution 3 - Java	Nathan S.	View Answer on Stackoverflow
Solution 4 - Java	Luis Tellez	View Answer on Stackoverflow

What is the difference between != and =! in Java?

Java Problem Overview

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Solution 1 - Java

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Solution 4 - Java

How to return an array from an AJAX call?

Change primary key column in SQL Server

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