PHP STATIC VARIABLES

What is a variable?

Variables in a program are used to store a few qualities or information that can be used later in a program. The variables are additionally similar to compartments that store character values, numeric qualities, memory locations, as well as strings. PHP has its own specific manner of announcing and putting away variables.

There are not many standards that should be followed and realities that should be remembered while managing variables in PHP:

Any variables declared in PHP should start with a dollar sign ($), trailed by the variable name.
A variable can have long illustrative names (like $factorial, $even_nos) or short names (like $n or $f or $x)
A variable name can contain alphanumeric characters and highlights (i.e., ‘a-z’, ‘A-Z’, ‘0-9 and ‘_’) in their name. Indeed, even it can’t begin with a number.
A steady is utilized as a variable for an essential worth that cannot be changed. It is additionally case-delicate.
The task of variables is finished with the task administrator, “equivalent to (=).” The variable names are on the left of the equivalent, and the articulation or values are to the right of the task administrator ‘=’.
One should remember that variable names in PHP names should begin with a letter or highlight and no numbers.
PHP is an inexactly composed language, and we don’t need to announce the information sorts of variables. Instead PHP accepts it naturally by investigating its qualities. The equivalent occurs during change. No variables are proclaimed before they are utilized. It consequently switches types starting with one sort over entirely and then onto the next at whatever point required.
PHP variables are case-delicate, i.e., $sum and $SUM are dealt with in an unexpected way.

Data types utilized by PHP to declare or build variables:

Null
Doubles
Integers
Strings
Booleans
Resources
Objects
Arrays

For example:

  <!DOCTYPE html>  <html>  <body>    <?php    // These are legitimate announcements  $val = 5;  $val2 = 2;  $op_qr_st = “string”;  $_QWERT = “new string”;    echo $val;  echo “<br>”;  echo $val2;  echo “<br>”;  echo $op_qr_st;  echo “<br>”;  echo $_QWERT;    // This is an invalid statement as it starts with a number  //$10_ val = 56;    // This is additionally invalid as it contains  // extraordinary person other than _  //$f.d = “num”;    ?>    </body>  </html>  

Output:

Variable Scopes

The extent of a variable is characterized as its degree in the program inside, which it very well may be gotten to. For example, the extent of a variable is the part of the program inside which it is apparent or can be gotten to.

Contingent upon the degrees, PHP has three variable extensions:

Local variables
Global variables
Static variables.

Local variables

The variables pronounced inside a function are called nearby variables to that function and have its extension just in that specific function. In short words, it can’t be gotten outside that function. Any statement of a variable external to the function with the same name as that of the one inside the function is something else entirely. We will find out about capacities exhaustively in later articles. For the present, think about a function as a square of explanations.

Example of Local Variables

  <?php    $num = 60;    function local_var()  {      // This $num is nearby to this function      // the variable $num outside this function      // is something else entirely      $num = 50;      echo “nearby num = $num n”;  }    local_var();    // $num outside work local_var() is a  // totally unexpected Variable in comparison to that of  // inside local_var()  echo “Variable num outside local_var() is $num n”;    ?>  

Output:

In the above example, we have created a local variable $num and displayed the use of the local variable both inside the function as well as outside it and found that it can only work in the local scope of a function.

Global variables

The variables announced externally in a function are called global variables. These variables can be gotten to straightforwardly outside a function. To get access inside a function, we want to utilize the “global” catchphrase before the variable to allude to the global variable.

Example of Global Variables

  <?php    $num = 20;    // function to exhibit utilization of global variable  function global_var()  {      // we need to utilize global catchphrase previously      // the variable $num to access inside      // the function      global $num;       echo “Variable num inside work : $num n”;  }    global_var();    echo “Variable num outside work : $num n”;    ?>  

Output:

In the above example, we have created a global variable $num and display the use of the global variable both inside the function as well as outside it.

Static Variables

The last kind of factor perusing that I examine is known as static. Rather than the variables announced as function boundaries, which are annihilated on the function’s leave, a static variable won’t lose its worth when the function exits and will, in any case, hold that worth should the function be called once more.

You can pronounce a variable to be static just by putting the watchword STATIC before the variable name.

A static variable is the attribute of PHP to erase the variable once it finishes its execution and the memory is liberated. However, in some cases, we really want to store the variables even after the fulfillment of function execution. To do this, we utilize a static catchphrase, and the variables are then called static variables. PHP partners an information type contingent upon the incentive for the variable.

  <?php     function keep_track() {        STATIC $count = 0;        $count++;        print $count;        print “<br/>”;     }       keep_track();     keep_track();     keep_track();  ?>  

This will deliver the accompanying outcome ?

You must have noticed that $ regularly counts increments even after the first function call, but This is because $sum is static, and its memory is not freed after the execution of the first function call.

Example of Static Variables

  <?php    // function to exhibit static variables  function static_var()  {      // static variable      static $num = 5;      $total = 2;        $sum++;      $num++;        echo $num, “n”;      echo $sum, “n”;  }    // first function call  static_var();    // second function call  static_var();    ?>  

Output:

You probably saw that $num routinely augments even after the main function call, yet $sum doesn’t. This is on the grounds that $sum isn’t static, and its memory is liberated after the execution of the first function call.

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PHP STATIC VARIABLES

PHP STATIC VARIABLES

What is a variable?

Variable Scopes

Local variables

Global variables

Static Variables

PHP Imagestring() Function

PHP Example

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