Add content for PHP strings (#27489)

* Add content for PHP strings

* fix: resolved conflict

guide/english/php/strings/index.md

@@ -2,12 +2,51 @@
 title: Strings
 ---
 ## Strings
-A string is a sequence of characters, like "Hello world!".
 
-## PHP String Functions
+A string is series of characters. These can be used to store any textual information in your application.
+
+There are a number of different ways to create strings in PHP.
+
+### Single Quotes
+
+Simple strings can be created using single quotes.
+```PHP
+$name = 'Joe';
+```
+
+To include a single quote in the string, use a backslash to escape it.
+
+```PHP
+$last_name = 'O\'Brian';
+```
+
+
+### Double Quotes
+
+You can also create strings using double quotes.
+```PHP
+$name = "Joe";
+```
+
+To include a double quote, use a backslash to escape it.
+
+```PHP
+$quote = "Mary said, \"I want some toast,\" and then ran away.";
+```
+
+Double quoted strings also allow escape sequences. These are special codes that put characters in your string that represent typically invisible characters. Examples include newlines `\n`, tabs `\t`, and actual backslashes `\\`.
+
+You can also embed PHP variables in double quoted strings to have their values added to the string.
+```PHP
+$name = 'Joe';
+$greeting = "Hello $name"; // now contains the string "Hello Joe"
+```
+
+
+### PHP String Functions
 In this chapter we will look at some commonly used functions to manipulate strings.
 
-## Get The Length of a String
+#### Get The Length of a String
 The PHP strlen() function returns the length of a string.
 The example below returns the length of the string "Hello world!":
 ````
@@ -18,7 +57,7 @@ echo strlen("Hello world!"); // outputs 12
 A string is series of characters.
 PHP only supports a 256-character set and hence does not offer native Unicode support.
 
-## Count The Number of Words in a String
+#### Count The Number of Words in a String
 The PHP str_word_count() function counts the number of words in a string:
 ````
 <?php
@@ -26,7 +65,7 @@ echo str_word_count("Hello world!"); // outputs 2
 ?>
 ````
 
-## Reverse a String
+#### Reverse a String
 The PHP strrev() function reverses a string:
 ````
 <?php
@@ -34,7 +73,7 @@ echo strrev("Hello world!"); // outputs !dlrow olleH
 ?>
 ````
 
-## Search For a Specific Text Within a String
+#### Search For a Specific Text Within a String
 The PHP strpos() function searches for a specific text within a string.
 If a match is found, the function returns the character position of the first match. If no match is found, it will return FALSE.
 The example below searches for the text "world" in the string "Hello world!":
@@ -44,12 +83,14 @@ echo strpos("Hello world!", "world"); // outputs 6
 ?>
 ````
 
-## Replace Text Within a String
+#### Replace Text Within a String
 ````
 <?php
 echo str_replace("world", "Dolly", "Hello world!"); // outputs Hello Dolly!
 ?>
 ````
 
-#### More Information:
-[PHP String tutorial](https://www.w3schools.com/php/php_string.asp)
+### More Information:
+<!-- Please add any articles you think might be helpful to read before writing the article -->
+* [PHP: Strings](http://php.net/manual/en/language.types.string.php)
+* [PHP String tutorial](https://www.w3schools.com/php/php_string.asp)