(i) It is used to loop through each KEY value pair in an array.
(ii) It will issue an error when you try to use it on a variable with a different data type or an initialized variable.

Syntax of for each loop
for each (＄array as ＄value)
{
code to be executed;
}

(i) for loop
(ii) for each loop
(iii) while loop
(iv) Do while loop

For each loop is exclusively available in PHP and is mainly used for looping through the values of an array. The loop iteration deepens on each KEY Value pair in the Array. For each, loop iteration the value of the current array element is assigned to $value variable and the array pointer is advanced by one, until it reaches the end of the array element.

Loop structures in PHP is an iterative control structures that involves executive the same block of code a specified number of times. Loops that iterate for fixed no of times is also called as Bounded loops.

< ?php
for (＄x = 0; ＄x < = 5; ＄x++)
{
 echo "Hello World < br >";
}
? >

(i) PHP Loop Often when you write code, you want the same block of code to run over and over again in a row.
(ii) Instead of adding several almost equal code-lines in a script, we can use loops to perform a task.
(iii) Looping structures are useful for writing iteration logics.
(iv) It is the most important feature of many programming languages, including PHP.

'for loop' is called as the entry-check loop.
The for loop is used to execute a block of code a specific number of times.
Syntax:
for (initialization; condition; increment / decrement) 
{
          //code to be executed;
}
The initialization part is executed only once at the beginning of the loop. It is used to initialize variables. The condition is evaluated before each iteration of the loop. If it is true, the code block is executed. If it is false, the loop is terminated. The increment/ decrement part is executed after each iteration of the loop. It is used to update variables.
Example 1
To print the numbers from 1 to 5 in ascending order
for (i = 1; i<=5; i++)
{
          echo i. "<br>";
}
Output:
1
2
3
4
5
Example 2
To print the numbers from 5 to 1 in descending order
for (i = 5; i<=1; i--)
{
          echo i. "<br>";
}
Output:
5
4
3
2
1

Looping structure are useful for writing iteration logics. It is the most important feature of many programming languages including PHP.
Looping categories are
(i) for loop
(ii) for each loop
(iii) while loop
(iv) Do while loop
(i) for loop:
It is used for iteration logics when the programmer know in advance how many times the loop should run.
Syntax:
for (init counter; test counter; increment counter)
{
code to be executed;
}
Parameters:
init counter: To initialize the loop initial counter value
test counter : Evaluated for every iteration, of the loop.
If it evaluates to TRUE, the loop continues.
If it evaluates to FALSE, the loops ends.
Increment counter:Increases the loop counter value.

(ii) for each loop:
It works only with arrays.
Loop iteration depends on each KEY value pair in the Array.
In loop iteration, value of the current array element is assigned to $value variable and the array
pointer is shifted by one until it reaches the end of the array element.
Syntax:
for each ($array as $value)
{
code to be executed;
}
(iii) While loop:
It is used for simple iteration logics.
It checks the condition, if the condition is true, and it executes the loop.
Syntax:
while (condition is true)
code to be executed;
}
(iv) Do while loop:
Do while loop always run the statement inside the loop block at the first time of execution. It then checks the condition. If the specified condition is true, it executes the loop.
Syntax:
do
{
code to be executed;
}while (condition is true);
}