Introduction to Array

When creating long, complex programs, it sometimes becomes difficult to access certain elements in a program. for example there is a limitation for using variables in a program: when you declare a variable, you can assign only one value to it. In certain case , you may want to declare hundreds of variables and it may not be possible to remember each and every variable and use it. Array help to accomplish this. An array is a special kind of variable that unlike conventional variables, can store multiple values that are indexed. To understand this definition let it split it into three parts:.
- An array is a special kind of variable because it is primarily use for strong values.
- Unlike conventional variables, array can store multiple values without any limitation.
- Each value that is assigned to an array is accessed using an index in the form of a number or a string.

Features of Arrays

There are a few underlying features of array that help qualify them as one of the most important elements in any complex program.
- Any number of values can be stored in a single array.
- The value stored in an array can be numeric or string.
- After the value are stored in the array, they can be extracted from it at any given time.
- Arrays enhance the scope and flexibility of a program by allowing data to be accessed easily.
- Array organize complex datastructure that are related in some way.
- It is possible to add values to an array after it is created. which is not possible in case of a variable.
- Values in an array can be retrieved sequentially and randomly.

CREATING A SIMPLE ARRAY

Creating an array is as simple as creating a variable. The only difference is that its main purpose is to hold multiple related values in the same place. consider the fallowing example

<?php
     $week[] = "Sunday";
     $week[] = "Monday";
     $week[] = "Tuesday"; /* And So on */  
?>

Declaring an array by using the array () function

<?php
  $week = array("Sunday", "Monday", "Tuesday","etc..");
?>

ASSOCIATIVE ARRAYS

Arrays that are indexed by using strings are called associative arrays. When you use them, you specified a string instead of number within the square brackets.

<?php
   $student[Name] = "Rishi";
   $student[Age] = "8";
   $student[Game] = "Chess";
?>
OR
<?php
   $student = array(Name=>"Rishi", Age=>"8", Game=>"Chess");
?>

MULTIDIMENSIONAL ARRAYS

As discuss earlier, array can store numbers as well as names. They can also store other arrays. Such arrays are multidimensional arrays or an array of arrays.

<?php
 $student = array(
 array( Name=>"Rishi", Age=>"8", Game=>"Chess"),
 array( Name=>"Sambit", Age=>"9", Game=>"Chess"),
 array( Name=>"Rupal", Age=>"10", Game=>"Chess"),   
);

echo $student[1][Age];
?>

Output: 9;

Looping through arrays

Another method of accessing the elements in an array and displaying them is by looping. You can use the foreach statement to loop through enumerated, associative and multidimensional arrays.

Looping through an enumerated array

As discuss earlier, the foreach statement comes in handy when looping through an enumerated array. Consider the fallowing example
<?php
foreach ($array as $val){
  echo "My Value=".$val ."<br/>";
}
?>

Looping through an associative array

The foreach statement is also used for looping through an associative arrays, but there is a slight change in the way you use it. You would need to specified the key as well as the value of an element to access a particular element. consider an example
<?php
foreach ($array as $key =>$val){
  echo " $key = $val <br/>";
}
?>

Displaying a multidimensional array

After learning how to loop through enumerated arrays and associative arrays, you might want to know how to loop through a multidimensional arrays. You can combine your knowledge to looping through enumerated and associative arrays to accomplish this.

<?php
 $student = array(
 array( Name=>"Rishi", Age=>"8", Game=>"Chess"),
 array( Name=>"Sambit", Age=>"9", Game=>"Chess"),
 array( Name=>"Rupal", Age=>"10", Game=>"Chess"),   
);
foreach($student as $st){
 foreach($st as $key => $val){
   echo "$key = $val"."<br/>";
  }
 echo "<hr>";
}
?>

Output:
Name = Rishi
Age = 8
Game = Chess
-------------------------------------
Name = Sambit
Age = 9
Game = Chess
--------------------------------------
Name = Rupal
Age = 10
Game = Chess



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