The `g` stands for global, as in replace globally (all):

In irb:

    &gt;&gt; &quot;hello&quot;.sub(&#39;l&#39;, &#39;*&#39;)
    =&gt; &quot;he*lo&quot;
    &gt;&gt; &quot;hello&quot;.gsub(&#39;l&#39;, &#39;*&#39;)
    =&gt; &quot;he**o&quot;


The difference is that `sub` only replaces the first occurrence of the pattern specified, whereas `gsub` does it for all occurrences (that is, it replaces globally). 

    value = &quot;abc abc&quot;
    puts value                                # abc abc
    # Sub replaces just the first instance.
    value = value.sub(&quot;abc&quot;, &quot;---&quot;)
    puts value                                # --- abc
    # Gsub replaces all instances.
    value = value.gsub(&quot;abc&quot;, &quot;---&quot;)
    puts value                                # --- ---

`sub` and `gsub` perform replacement of the first and all matches respectively.


    sub(pattern, replacement, x, ignore.case = FALSE, perl = FALSE,
        fixed = FALSE, useBytes = FALSE)
    
    gsub(pattern, replacement, x, ignore.case = FALSE, perl = FALSE,
         fixed = FALSE, useBytes = FALSE)


    sub(&quot;4&quot;, &quot;8&quot;, &quot;An Introduction to R Software Course will be of 4 weeks duration&quot; )  
    ##&quot;An Introduction to R Software Course will be of 8 weeks duration&quot;

    gsub(&quot;4&quot;, &quot;8&quot;, &quot;An Introduction to R Software Course will be of 4 weeks duration&quot; )
    ##&quot;An Introduction to R Software Course will be of 8 weeks duration&quot;



Since on an iPad we cannot edit the hosts file (without jailbreaking), how can we arbitrarily redirect web traffic to another url?

This would be important for something such as developing a website that uses a Virtual Host configuration where you want to redirect to a development machine.

(This is related to this question: [Can I edit an iPad&#39;s host file?][1])


  [1]: https://stackoverflow.com/questions/4783923/can-i-edit-an-ipads-host-file

How can I redirect HTTP requests made from an iPad?

I most commonly am tempted to use &quot;bastard injection&quot; in a few cases.  When I have a &quot;proper&quot; dependency-injection constructor:

    public class ThingMaker {
        ...
        public ThingMaker(IThingSource source){
            _source = source;
        }

But then, for classes I am intending as **public APIs** (classes that other development teams will consume), I can never find a better option than to write a default &quot;bastard&quot; constructor with the most-likely needed dependency:

        public ThingMaker() : this(new DefaultThingSource()) {} 
        ...
    }

The obvious drawback here is that this creates a static dependency on DefaultThingSource; ideally, there would be no such dependency, and the consumer would always inject whatever IThingSource they wanted.  However, this is too hard to use; consumers want to new up a ThingMaker and get to work making Things, then months later inject something else when the need arises.  This leaves just a few options in my opinion:

 1. Omit the bastard constructor; force the consumer of ThingMaker to understand IThingSource, understand how ThingMaker interacts with IThingSource, find or write a concrete class, and then inject an instance in their constructor call. 
 2. Omit the bastard constructor and provide a separate factory, container, or other bootstrapping class/method; somehow make the consumer understand that they don&#39;t need to write their own IThingSource; force the consumer of ThingMaker to find and understand the factory or bootstrapper and use it.
 3. Keep the bastard constructor, enabling the consumer to &quot;new up&quot; an object and run with it, and coping with the optional static dependency on DefaultThingSource.

Boy, #3 sure seems attractive.  Is there another, better option?  #1 or #2 just don&#39;t seem worth it.

Is there an alternative to bastard injection? (AKA poor man&#39;s injection via default constructor)

I have been perusing the documentation for `String` today, and I saw the `:sub` method, which I&#39;d never noticed before.  I&#39;ve been using `:gsub` and it appears that they are essentially the same.  Can anyone explain the difference to me?  Thanks!

What is the difference between gsub and sub methods for Ruby Strings

<p>I have been perusing the documentation for <code>String</code> today, and I saw the <code>:sub</code> method, which I'd never noticed before.  I've been using <code>:gsub</code> and it appears that they are essentially the same.  Can anyone explain the difference to me?  Thanks!</p>


Is there an alternative to `update_attributes` that does not save the record?

So I could do something like:

    @car = Car.new(:make =&gt; &#39;GMC&#39;)
    #other processing
    @car.update_attributes(:model =&gt; &#39;Sierra&#39;, :year =&gt; &quot;2012&quot;, :looks =&gt; &quot;Super Sexy, wanna make love to it&quot;)
    #other processing
    @car.save

BTW, I know I can `@car.model = &#39;Sierra&#39;`, but I want to update them all on one line.

Rails update_attributes without save?

How can I force a subclass to implement a method in Ruby. There doesn&#39;t seem to be an abstract keyword in Ruby, which is the approach I would take in Java. Is there another more Ruby-like way to enforce abstract? 

Abstract Method in Ruby

I have done all kinds of research and tried many different things. I know this question has been answered many times, but none of the suggested solutions are working for me.

After upgrading to Lion I am getting segmentation faults in Ruby. I&#39;m fairly confident it&#39;s Nokogiri. So I installed libxml2 via Homebrew. I ran `brew link libxml2`. Then I reinstalled Nokogiri using that version of the library.

For proof:

    $ nokogiri -v
    # Nokogiri (1.5.0)
    ---
    warnings: []
    nokogiri: 1.5.0
    ruby:
      version: 1.9.2
      platform: x86_64-darwin11.0.0
      description: ruby 1.9.2p290 (2011-07-09 revision 32553) [x86_64-darwin11.0.0]
      engine: ruby
    libxml:
      binding: extension
      compiled: 2.7.8
      loaded: 2.7.8

I&#39;ve already included Nokogiri at the top of my gemfile and I&#39;ve also required it in my environment file. I have no idea why I am still getting that warning.

Any suggestions or ideas to make sure it&#39;s loading the right version libxml2?


Mac user and getting WARNING: Nokogiri was built against LibXML version 2.7.8, but has dynamically loaded 2.7.3

I know that I can write a Ruby case statement to check a match against a regular expressions.
However, I&#39;d like to use the match data in my return statement. Something like this semi-pseudocode:

    foo = &quot;10/10/2011&quot;
    
    case foo
        when /^([0-9][0-9])/
            print &quot;the month is #{match[1]}&quot;
        else
            print &quot;something else&quot;
    end

How can I achieve that?

Thanks!


----------

Just a note: I understand that I wouldn&#39;t ever use a switch statement for a simple case as above, but that is only one example. In reality, what I am trying to achieve is the matching of many potential regular expressions for a date that can be written in various ways, and then parsing it with Ruby&#39;s Date class accordingly.



How to write a Ruby switch statement (case...when) with regex and backreferences?

I have a Rails 3.0.9 app that, once it is deployed, suffers from a bunch of ActiveModel::MissingAttributeErrors that crop up causing 500s. The errors occur fairly randomly, sometimes a page will load, other times it won&#39;t, but the attributes are all existing attributes in the database and should be found.

The strange part is that after a while, the errors go away. Suddenly, they stop causing an issue.

I have searched about for a solution to this, but this error mostly occurs either when someone has done `Model.all(:select =&gt; &#39;column_x,column_y&#39;)` and are calling for `column_z` or when they are using cache_money. I am doing neither of these things.

Can anyone help?


ActiveModel::MissingAttributeError occurs after deploying and then goes away after a while

In the book &quot;Effective Java&quot;, Josh Bloch says that 

&gt; StringBuffer is largely obsolete and should be replaced by the
&gt; non-synchronized implementation &#39;StringBuilder&#39;

. 

But in my experience, I&#39;ve still seen widespread use of the StringBuffer class. Why is the StringBuffer class now obsolete and why should StringBuilder be preferred over StringBuffer except for the increased performance due to non-synchronization?

StringBuffer is obsolete?

Is there a way to convert a string to lowercase? 

```
&quot;Kilometers&quot;  →  &quot;kilometers&quot;
```



How do I lowercase a string in Python?

How can I search and replace a String in all files of my current project?

Let&#39;s say I have the string &quot;/sites/default/&quot; now I want it to be &quot;/public/sites/default/&quot;, but there are almost 1000 files.

Replace String in all files in Eclipse

Can someone explain why this works with the pointer: 

    char * str1;

    str1 = &quot;Hello1&quot;;

    str1 = &quot;new string&quot;;
    
    // but not this
    char str2 [] = &quot;hello&quot;;
    str2 = &quot;four&quot;;
    
    // or this
    char str3 [];
    str3 = &quot;hello&quot;;
    str3 = &quot;hello&quot;;

    


Why can a string be assigned to a char* pointer, but not to a char[] array?

I have the following piece of code:

    $item[&#39;price&#39;] = 0;
    /* Code to get item information goes in here */
    if($item[&#39;price&#39;] == &#39;e&#39;) {
        $item[&#39;price&#39;] = -1;
    }

It is intended to initialize the item price to 0 and then get information about it. If the price is informed as &#39;e&#39; it means an exchange instead of a sell, which is stored in a database as a negative number.

There is also the possibility to leave the price as 0, either because the item is a bonus or because the price will be set in a later moment.

But, whenever the price is not set, which leaves it with the initial value of 0, the ```if``` loop indicated above evaluates as true and the price is set to -1. That is, it considers 0 as equal to &#39;e&#39;.

How can this be explained?

When the price is provided as 0 (after initialization), the behavior is erratic: sometimes the if evaluates as true, sometimes it evaluates as false.*





Content Type	Original Author	Original Content on Stackoverflow
Question	Ryanmt	View Question on Stackoverflow
Solution 1 - Ruby	Ray Toal	View Answer on Stackoverflow
Solution 2 - Ruby	Chris Bunch	View Answer on Stackoverflow
Solution 3 - Ruby	deepak	View Answer on Stackoverflow
Solution 4 - Ruby	HEMANTHKUMAR GADI	View Answer on Stackoverflow

What is the difference between gsub and sub methods for Ruby Strings

Ruby Problem Overview

Ruby Solutions

Solution 1 - Ruby

Solution 2 - Ruby

Solution 3 - Ruby

Solution 4 - Ruby

Is there an alternative to bastard injection? (AKA poor man's injection via default constructor)

How can I redirect HTTP requests made from an iPad?

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