Learn PHP

The management of strings is very important in any programming language;
there are several functions to manage strings, following is an explanation of the most widely used.

Strings can be created using single-quotes and double-quotes .

For example , both versions are correct and they produce the same result :

$string1 = "This is a test";

$string2 = 'This is a test';

A string can be displayed using echo :

echo $string1 ;

will display


This is a test

To concat two strings you need the dot ( . ) operator so in case you have a long string and for the sake of readability you have to cut it into two you can do it just like the example below.


$string=" this is "." a test ";

Most important string functions :

• strlen(string). returns number of characters inside the string including blank space. If you want blank space to be removed then you can apply string replace function str_replace to the string before applying strlen.
• split(separator,string). Divides a string into several, using a separation character.
• substr($string, $start, $end) : get a chunk of $string
  
  echo substr('123456789', 0, 2);
  
  Print 12

• str_repeat($string, $n) : repeat $string $n times
  
  echo str_repeat('a', 10); does the same thing as for ($i = 0; $i < 10; $i++) {
  echo 'a';
  }

• strrchr($string, $char) : find the last occurence of the character $char in $string
  
  You can get the file extension from a file name. You can use this function in conjunction with substr().
  
  $ext = substr(strrchr($filename, '.'), 1);
  
  For example , we have test.php . strrchr($filename, '.') returns .php and substr(".php",1) returns php

• trim($string) : remove extra spaces at the beginning and end of $string
• explode($separator, $string) : Split $string by $separator
  
  This function is commonly used to extract values in a string which are separated by a a certain separator string. For example, suppose we have some information stored as comma separated values.
  
  $string = 'Test1, 3 , 2005';
  
  $info = explode(',', $string);
  
  Variable $info is an array so we can access the values using $info[0], info[1] etc. For example $info[0]="Test1".

• implode($string, $array) : Join the values of $array using $string
  
  This one do the opposite than the previous function.

• number_format($number): display a number with grouped thousands
  
  echo number_format(15120777); displays display 15,120,777