&gt; Ruby has no pre/post increment/decrement operator. For instance, `x++` or `x--` will fail to parse. More importantly, `++x` or `--x` will do nothing! In fact, they behave as multiple unary prefix operators: `-x == ---x == -----x == ......` To increment a number, simply write `x += 1`.

Taken from &quot;Things That Newcomers to Ruby Should Know
&quot; ([archive][1], [mirror][2])

That explains it better than I ever could.

EDIT: and the reason from the language author himself ([source][3]):

&gt; 1. ++ and -- are NOT reserved operator in Ruby.
&gt; 2. C&#39;s increment/decrement operators are in fact hidden assignment. They affect variables, not objects. You cannot accomplish assignment via method. Ruby uses +=/-= operator instead.
&gt; 3. self cannot be a target of assignment.  In addition, altering the value of integer 1 might cause severe confusion throughout the program.


  [1]: https://web.archive.org/web/20160821135201/ruby.activeventure.com/newcomers/ruby.html
  [2]: https://www.cs.auckland.ac.nz/references/ruby/doc_bundle/Newcomers/ruby.html
  [3]: https://web.archive.org/web/20170421214136/blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/2710

From a [posting by Matz][1]:

&gt; (1) ++ and -- are NOT reserved
&gt; operator in Ruby.
&gt; 
&gt;   (2) C&#39;s increment/decrement
&gt; operators are in fact hidden
&gt; assignment.
&gt;       They affect variables, not objects.  You cannot accomplish
&gt;       assignment via method.  Ruby uses +=/-= operator instead.
&gt; 
&gt;   (3) self cannot be a target of
&gt; assignment.  In addition, altering
&gt;       the value of integer 1 might cause severe confusion throughout
&gt;       the program.
&gt; 
&gt; 							matz.


  [1]: http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/2710

I don&#39;t think that notation is available because—unlike say PHP or C—everything in Ruby is an object.

Sure you could use `$var=0; $var++` in PHP, but that&#39;s because it&#39;s a variable and not an object. Therefore, `$var = new stdClass(); $var++` would probably throw an error.

I&#39;m not a Ruby or RoR programmer, so I&#39;m sure someone can verify the above or rectify it if it&#39;s inaccurate.

How do I strip all the spaces in a python string? For example, I want a string like `strip my spaces` to be turned into `stripmyspaces`, but I cannot seem to accomplish that with `strip()`:

    &gt;&gt;&gt; &#39;strip my spaces&#39;.strip()
    &#39;strip my spaces&#39;

How to strip all whitespace from string

I want to encode an image into a string using the base64 module. I&#39;ve ran into a problem though. How do I specify the image I want to be encoded? I tried using the directory to the image, but that simply leads to the directory being encoded. I want the actual image file to be encoded. 

**EDIT**

I tried this snippet:

    with open(&quot;C:\Python26\seriph1.BMP&quot;, &quot;rb&quot;) as f:
        data12 = f.read()
        UU = data12.encode(&quot;base64&quot;)
        UUU = base64.b64decode(UU)
    
        print UUU
    
        self.image = ImageTk.PhotoImage(Image.open(UUU))

but I get the following error:

    Traceback (most recent call last):
      File &quot;&lt;string&gt;&quot;, line 245, in run_nodebug
      File &quot;C:\Python26\GUI1.2.9.py&quot;, line 473, in &lt;module&gt;
        app = simpleapp_tk(None)
      File &quot;C:\Python26\GUI1.2.9.py&quot;, line 14, in __init__
        self.initialize()
      File &quot;C:\Python26\GUI1.2.9.py&quot;, line 431, in initialize
        self.image = ImageTk.PhotoImage(Image.open(UUU))
      File &quot;C:\Python26\lib\site-packages\PIL\Image.py&quot;, line 1952, in open
        fp = __builtin__.open(fp, &quot;rb&quot;)
    TypeError: file() argument 1 must be encoded string without NULL bytes, not str

What am I doing wrong? 

Encoding an image file with base64

&gt; **Possible Duplicate:**  
&gt; [Why doesn&amp;#39;t Ruby support i++ or i&amp;mdash; for fixnum?](https://stackoverflow.com/questions/3660563/why-doesnt-ruby-support-i-or-i-for-fixnum)  

&lt;!-- End of automatically inserted text --&gt;

Why is there no increment operator in Ruby?

e.g.

    i++
    ++i

Is the `++` operator used for something else? Is there a *real* reason for this?

No increment operator (++) in Ruby?

> Possible Duplicate: 
> <a href="https://stackoverflow.com/questions/3660563/why-doesnt-ruby-support-i-or-i-for-fixnum" target="_blank" rel="noopener noreferrer">Why doesn't Ruby support i++ or i— for fixnum?</a>

Why is there no increment operator in Ruby?
e.g.
<pre><code class="hljs language-css">i++
++i
</code></pre>
Is the <code>++</code> operator used for something else? Is there a real reason for this?

I am having a hard time understanding what the shift and unshift methods of the Array class do in Ruby. Can somebody help me understand what they do?

What Does Ruby&#39;s Array#shift do?

The `upcase` method capitalizes the entire string, but I need to capitalize only the first letter.

Also, I need to support several popular languages, like German and Russian.

How do I do it?

How to capitalize the first letter in a String in Ruby

This is my array

    [{:amount=&gt;10, :gl_acct_id=&gt;1, :alt_amount=&gt;20}, {:amount=&gt;20, :gl_acct_id=&gt;2
    , :alt_amount=&gt;30}]

i want result 

    [{:amount =&gt; 30}] or {:amount = 30}

Any idea?

Sum the value of array in hash

What are the best uses for these 3 languages/frameworks? Is it useful to mix all of them (or 2)?



When to use node.js vs sinatra vs rails?

Is there a Python equivalent to Ruby symbols? 

 - If so then what is it?

 - If not then are we stuck with using **strings** as our **keys** in dictionaries only?

Is there a Python equivalent to Ruby symbols?

### What is this?

This is a collection of questions that come up every now and then about syntax in PHP. This is also a Community Wiki, so everyone is invited to participate in maintaining this list. 

### Why is this?

It used to be hard to find questions about operators and other syntax tokens.&#185;  
The main idea is to have links to existing questions on Stack Overflow, so it&#39;s easier for us to reference them, not to copy over content from the PHP Manual.

Note: Since January 2013, Stack Overflow [does support special characters][1]. Just surround the search terms by quotes, e.g. [`[php] &quot;==&quot; vs &quot;===&quot;`][2]

### **What should I do here?**

If you have been pointed here by someone because you have asked such a question, please find the particular syntax below. The linked pages to the [PHP manual](http://php.net/manual/en/index.php) along with the linked questions will likely answer your question then. If so, you are encouraged to upvote the answer. This list is not meant as a substitute for the help others provided.

## The List

If your particular token is not listed below, you might find it in the [List of Parser Tokens][3].

---

`&amp;` [Bitwise Operators][4] or [References][5]

 - https://stackoverflow.com/questions/1676897
 - https://stackoverflow.com/questions/600202
 - https://stackoverflow.com/questions/2209934/
 - https://stackoverflow.com/questions/2376348
 - https://stackoverflow.com/questions/1006652
 - https://stackoverflow.com/questions/2297592
 - https://stackoverflow.com/questions/2422907
 - https://stackoverflow.com/questions/2478149
 - https://stackoverflow.com/questions/3957584
 - https://stackoverflow.com/questions/4705262
 - https://stackoverflow.com/questions/4705838
 - https://stackoverflow.com/questions/21058439 (&amp;$)

---

`=&amp;` [References][5]

 - https://stackoverflow.com/questions/1768343
 - https://stackoverflow.com/questions/1367454
 - https://stackoverflow.com/questions/3177342
 - https://stackoverflow.com/questions/2081806

---

`&amp;=` [Bitwise Operators][4]

 - https://stackoverflow.com/questions/1367454
 - https://stackoverflow.com/questions/3177342

---

`&amp;&amp;` [Logical Operators][6]

 - https://stackoverflow.com/questions/2803321
 - https://stackoverflow.com/questions/2376348
 - https://stackoverflow.com/questions/4746865
 - https://stackoverflow.com/questions/4502092

---

`%` [Arithmetic Operators][7]

 - https://stackoverflow.com/questions/1934173
 - https://stackoverflow.com/questions/3204919

---

`!!` [Logical Operators][6]

 - https://stackoverflow.com/questions/2127260

---

`@` [Error Control Operators][8]

 - https://stackoverflow.com/questions/1032161
 - https://stackoverflow.com/questions/3551527
 - https://stackoverflow.com/questions/3984864
 - https://stackoverflow.com/questions/4872340
 - https://stackoverflow.com/questions/3621215

---

`?:` [Ternary Operator][9]

 - https://stackoverflow.com/questions/1080247
 - https://stackoverflow.com/questions/1993409
 - https://stackoverflow.com/questions/4055355
 - https://stackoverflow.com/questions/4210187

---

`??` [Null Coalesce Operator][36] (since PHP 7)

 - https://stackoverflow.com/questions/7278835

---

`?string`
`?int`
`?array`
`?bool`
`?float` [Nullable return type declaration][10] (since PHP 7.1)

 - [Nullable return type declaration](https://stackoverflow.com/a/54217328/250259)
 - [Nullable parameter type declaration](https://stackoverflow.com/a/48450841)
 - [php method argument type hinting with question mark (?type)][34]

---

`:` [Alternative syntax for control structures][11], [Ternary Operator][9], [Return Type Declaration](https://www.php.net/manual/en/language.types.declarations.php)

 - https://stackoverflow.com/questions/2908095
 - https://stackoverflow.com/questions/4747761
 - https://stackoverflow.com/questions/40346754

---

`::` [Scope Resolution Operator][12]

 - https://stackoverflow.com/questions/2903564
 - https://stackoverflow.com/questions/2588298
 - https://stackoverflow.com/questions/3173501
 - https://stackoverflow.com/questions/1912902
 - https://stackoverflow.com/questions/4120755
 - https://stackoverflow.com/questions/8734823

---

`\` [Namespaces][13]

 - https://stackoverflow.com/questions/10788400
 - https://stackoverflow.com/questions/4790020

---

`-&gt;` [Classes And Objects][14]

 - https://stackoverflow.com/questions/2588149
 - https://stackoverflow.com/questions/3037526
 - https://stackoverflow.com/questions/3173501
 - https://stackoverflow.com/questions/2316370
 - https://stackoverflow.com/questions/4502587

---

`=&gt;` [Arrays][15]

 - https://stackoverflow.com/questions/1241819
 - https://stackoverflow.com/questions/1655336
 - https://stackoverflow.com/questions/4758791

---

`^` [Bitwise Operators][4]

 - https://stackoverflow.com/questions/2674920
 - https://stackoverflow.com/questions/2724936

---

`&gt;&gt;` [Bitwise Operators][4]

 - https://stackoverflow.com/questions/2790329

---

`&lt;&lt;` [Bitwise Operators][4]

- https://stackoverflow.com/questions/9718689/strange-print-behaviour-in-php

---

`&lt;&lt;&lt;` [Heredoc or Nowdoc][16]

 - https://stackoverflow.com/questions/5539669
 - https://stackoverflow.com/questions/1048481
 - https://stackoverflow.com/questions/3700042
 - https://stackoverflow.com/questions/2090081
 - https://stackoverflow.com/questions/2333779

---

`=` [Assignment Operators][17]

 - https://stackoverflow.com/questions/2063480

---

`==` [Comparison Operators][18]

 - https://stackoverflow.com/questions/80646
 - https://stackoverflow.com/questions/1663451
 - https://stackoverflow.com/questions/2063480
 - https://stackoverflow.com/questions/15813490/

---

`===` [Comparison Operators][18]

 - https://stackoverflow.com/questions/1117967
 - https://stackoverflow.com/questions/80646
 - https://stackoverflow.com/questions/2063480
 - https://stackoverflow.com/questions/15813490/

---

`!==` [Comparison Operators][18]

 - https://stackoverflow.com/questions/1298083
 - https://stackoverflow.com/questions/1139154

---

`!=` [Comparison Operators][18]

 - https://stackoverflow.com/questions/1663451
 - https://stackoverflow.com/questions/1139154
 - https://stackoverflow.com/questions/6356826
 - https://stackoverflow.com/questions/9671785/what-is-the-difference-between-and

---

`&lt;&gt;` [Comparison Operators][18]

 - https://stackoverflow.com/questions/249312
 - https://stackoverflow.com/questions/589391
 - https://stackoverflow.com/questions/9671785
 - https://stackoverflow.com/questions/15813490/

---

`&lt;=&gt;` [Comparison Operators][18] (since PHP 7.0)

 - [Spaceship (three way comparison) operator][19]

---

`|` [Bitwise Operators][4]

 - https://stackoverflow.com/questions/2233835
 - https://stackoverflow.com/questions/13811922

---

`||` [Logical Operators][6]

 - https://stackoverflow.com/questions/2233835
 - https://stackoverflow.com/questions/4502092
 - https://stackoverflow.com/questions/5666741
 - https://stackoverflow.com/questions/12213283

---

`~` [Bitwise Operators][4]

 - https://stackoverflow.com/questions/1967360

---

`+` [Arithmetic Operators][7], [Array Operators][20]

 - https://stackoverflow.com/questions/2140090

---

`+=` and `-=` [Assignment Operators][17]

 - https://stackoverflow.com/questions/542995
 - https://stackoverflow.com/questions/7140158

---

`++` and `--` [Incrementing/Decrementing Operators][21]

 - https://stackoverflow.com/questions/1968371
 - [Answer below][22]

---

`.=` [Assignment Operators][17]

 - https://stackoverflow.com/questions/2202331
 - https://stackoverflow.com/questions/1241432

---

`.` [String Operators][23]

 - https://stackoverflow.com/questions/1466408
 - https://stackoverflow.com/questions/6484968

---

`,` [Function Arguments][24]

 - https://stackoverflow.com/questions/1466408

`,` [Variable Declarations][25]

 - https://stackoverflow.com/questions/41383218

---

`$$` [Variable Variables][26]

 - https://stackoverflow.com/questions/2715654
 - https://stackoverflow.com/questions/4169882
 - https://stackoverflow.com/questions/4891872

---

`` ` `` [Execution Operator][27]

 - https://stackoverflow.com/questions/6002296

---

`&lt;?=` [Short Open Tags][28]

 - https://stackoverflow.com/questions/1963901
 - https://stackoverflow.com/questions/2020445
 - https://stackoverflow.com/questions/1959256/what-does-mean

---

`[]` [Arrays][15] (short syntax since PHP 5.4)

 - https://stackoverflow.com/q/20709055/2758197
 - https://stackoverflow.com/questions/6933345
 - https://stackoverflow.com/questions/2431629
 - https://stackoverflow.com/questions/3908576
 - [Shorthand for arrays: literal `$var = []` empty array](https://stackoverflow.com/questions/4271874)


---

`&lt;?` [Opening and Closing tags][29]

 - https://stackoverflow.com/questions/200640


---

`...` [Argument unpacking][30] (since PHP 5.6)

---
`**` [Exponentiation][31] (since PHP 5.6)

---
`#` [One-line shell-style comment][32]

 - [Can I use hashes for comments in PHP?][33]

---
`?-&gt;` [NullSafe Operator Calls][35] (since PHP 8.0)

- https://stackoverflow.com/questions/62178354/what-does-this-symbol-mean-in-php-within-an-object-or-null-value

---


  [1]: https://meta.stackexchange.com/questions/160100/a-new-search-engine-for-stack-exchange
  [2]: https://stackoverflow.com/search?q=%5Bphp%5D%20%22===%22%20vs%20%22==%22
  [3]: http://secure.php.net/manual/en/tokens.php
  [4]: http://secure.php.net/manual/en/language.operators.bitwise.php
  [5]: http://secure.php.net/manual/en/language.references.php
  [6]: http://secure.php.net/manual/en/language.operators.logical.php
  [7]: http://secure.php.net/manual/en/language.operators.arithmetic.php
  [8]: http://secure.php.net/manual/en/language.operators.errorcontrol.php
  [9]: http://php.net/manual/en/language.operators.comparison.php#language.operators.comparison.ternary
  [10]: https://www.php.net/manual/en/migration71.new-features.php
  [11]: http://secure.php.net/manual/en/control-structures.alternative-syntax.php
  [12]: http://secure.php.net/manual/en/language.oop5.paamayim-nekudotayim.php
  [13]: http://php.net/namespaces
  [14]: http://secure.php.net/manual/en/language.oop5.php
  [15]: http://secure.php.net/manual/en/language.types.array.php
  [16]: http://php.net/manual/en/language.types.string.php#language.types.string.syntax.heredoc
  [17]: http://secure.php.net/manual/en/language.operators.assignment.php
  [18]: http://secure.php.net/manual/en/language.operators.comparison.php
  [19]: https://stackoverflow.com/a/31298778
  [20]: http://secure.php.net/manual/en/language.operators.array.php
  [21]: http://secure.php.net/manual/en/language.operators.increment.php
  [22]: https://stackoverflow.com/a/3737177
  [23]: http://secure.php.net/manual/en/language.operators.string.php
  [24]: http://php.net/manual/en/functions.arguments.php
  [25]: http://php.net/manual/en/language.variables.scope.php
  [26]: http://php.net/manual/en/language.variables.variable.php
  [27]: http://php.net/manual/en/language.operators.execution.php
  [28]: http://php.net/manual/en/ini.core.php#ini.short-open-tag
  [29]: http://secure.php.net/manual/en/language.basic-syntax.php
  [30]: http://php.net/manual/en/functions.arguments.php#functions.variable-arg-list
  [31]: http://secure.php.net/manual/en/migration56.new-features.php#migration56.new-features.exponentiation
  [32]: http://php.net/manual/en/language.basic-syntax.comments.php
  [33]: https://stackoverflow.com/questions/9093609/can-i-use-hashes-for-comments-in-php
  [34]: https://stackoverflow.com/questions/48881489/php-method-argument-type-hinting-with-question-mark-type
  [35]: https://stackoverflow.com/a/62178856/250259
  [36]: https://www.php.net/manual/en/migration70.new-features.php#migration70.new-features.null-coalesce-op

Reference — What does this symbol mean in PHP?

I have the following code:

    public class Tests {
    	public static void main(String[] args) throws Exception {
    		int x = 0;
    		while(x&lt;3) {
    			x = x++;
    			System.out.println(x);
    		}
    	}
    }

We know he should have writen just `x++` or `x=x+1`, but on `x = x++` it should first attribute `x` to itself, and later increment it. Why does `x` continue with `0` as value?

**--update**

Here&#39;s the bytecode:

    public class Tests extends java.lang.Object{
    public Tests();
      Code:
       0:	aload_0
       1:	invokespecial	#1; //Method java/lang/Object.&quot;&lt;init&gt;&quot;:()V
       4:	return
    
    public static void main(java.lang.String[])   throws java.lang.Exception;
      Code:
       0:	iconst_0
       1:	istore_1
       2:	iload_1
       3:	iconst_3
       4:	if_icmpge	22
       7:	iload_1
       8:	iinc	1, 1
       11:	istore_1
       12:	getstatic	#2; //Field java/lang/System.out:Ljava/io/PrintStream;
       15:	iload_1
       16:	invokevirtual	#3; //Method java/io/PrintStream.println:(I)V
       19:	goto	2
       22:	return
    
    }

I&#39;ll read about the [instructions][1] to try to understand...


  [1]: http://en.wikipedia.org/wiki/Java_bytecode_instruction_listings

Why does this go into an infinite loop?

Assuming

    boolean a = false;

I was wondering if doing:
    
    a &amp;= b; 

is equivalent to

    a = a &amp;&amp; b; //logical AND, a is false hence b is not evaluated.

or on the other hand it means

    a = a &amp; b; //Bitwise AND. Both a and b are evaluated.





Does the Java &amp;= operator apply &amp; or &amp;&amp;?

&gt; **Possible Duplicate:**  
&gt; [What does !! mean in ruby?](https://stackoverflow.com/questions/524658/what-does-mean-in-ruby)  

&lt;!-- End of automatically inserted text --&gt;

Hi,

I&#39;m new to Ruby and can&#39;t find anywhere description of what &quot;!!&quot; means. 

Here&#39;s an example:

    def signed_in?
      !!current_user
    end

If this is a double negative, why not to say:

    def signed_in?
      current_user
    end

Please help.

Ruby, !! operator (a/k/a the double-bang)

I understand it&#39;s an inside joke that&#39;s meant to stay (just like “`from __future__ import braces`”), but what exactly does it do?

Content Type	Original Author	Original Content on Stackoverflow
Question	Skizit	View Question on Stackoverflow
Solution 1 - Ruby	Dave	View Answer on Stackoverflow
Solution 2 - Ruby	mikej	View Answer on Stackoverflow
Solution 3 - Ruby	Martin Bean	View Answer on Stackoverflow

No increment operator (++) in Ruby?

Ruby Problem Overview

Ruby Solutions

Solution 1 - Ruby

Solution 2 - Ruby

Solution 3 - Ruby

Encoding an image file with base64

How to strip all whitespace from string

Attributions