PHP while loops execute a block of code while the specified condition is true.

The foreach construct provides an easy way to iterate over arrays

For loops execute a block of code a specified number of times.

Syntax of Do while loop
do
{
code to be executed;
} while (condition is true);

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

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.

1. PHP while loops execute a block of code while the specified condition is true.
2. The for loop is used when you knew in advance how many times the script should run.
3. The foreach loop works only en arrays, and is used to loop through each key/value pair in an array.
4. do ... while - loops through a block of code once, and then repeats the loop as long as the specified condition is true.

< ?php
scolors = array("red", "qreen", "blue'; "yellew'');
fereach (sectors as ＄value)
{
echo "svalue < br >";
}
? >

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

< ?php
＄x = 1;
while(＄x < = 10)
{
echo sx:
＄x++;
}
? >

1. Do whileloop always run the statement inside of the loop block at the first time execution.
2. Then it is checking the condition whether true or false.
3. It executes the loop, if the specified condition is true.
Syntax:
do
{code to executed;
}while (condition is true);

1. The array concepts in looping structure is used in for each loop.
2. For each loop is exclusively available in PHP. It works only with arrays.
3. The loop iteration depends on each KEY value pair in the array. In for each, loop iteration the value of the current array element is assigned to $value variable and the array pointer is shifted by one until it reaches the end of the array element.
4. For each works only on arrays and objects, and will issue an error when you try to use it on a variable with a different data type or an uninitialized variable.
Syntax:
for each ($ array as $ value)
{
code to be executed;
}
1. The for each statement is used to loop through arrays.
2. 'For each' pass the value of the current array element is assigned to $value and the array pointer is moved by one and in the next pass next element will be processed.
Example:
$array = array (1, 2, 3);
{
echo "Value is $value
";
}
?>
Output:
Value is 1
Value is 2
Value is 3

Do while loop always run the statement inside of the loop block at the first time of execution. Then it checks the condition whether true or false. It executes the loop, if the specified condition is true.
Syntax:
do
{
code to be executed;
} while (condition is true);
Example
\(\$\)Student_count = 10;
\(\$\)student_number= 1;
do
{
echo "The student number is: \(\$\)student_number
";
\(\$\)student_number++ ;
}
while(\(\$\)student_number< = \(\$\)Student_count);
?>

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);
}