Thursday, 6 August 2015

LOOP CONCEPT IN PHP

04:31


   FOR LOOP  CONCEPT:

For loop Syntax:

Syntax:

The syntax of for loop is PHP is as follows −
for (initialization; test condition; iteration statement){
   Statement(s) to be executed if test condition is true
}


FOR   LOOP  SYNTAX :

for (init counter; test counter; increment counter)
{
    code to be executed;
}

<?php

for($i=0; $i<5;$i++)

{


echo $i;


}


?>


For loop   Example   :

<?php
$a=5;
for($i=1;$i<=10;$i++)
{
echo "  5*".$i."==".$a*$i.'<br>';
}
?>
Output:
5*1==5
5*2==10
5*3==15
5*4==20
5*5==25
5*6==30
5*7==35
5*8==40
5*9==45
5*10==50






While LOOP concept:


while  loop syntax:

The syntax of while loop in JavaScript is as follows −

while (expression){
   Statement(s) to be executed if expression is true
}

WHILE    LOOP   SYNTAX:

The while loop executes a block of code as long as the specified condition is true.

While  (condition is true) 
{
    code  to be executed;
}

EXAMPLE  :

<?php

$i=0;

while($i<5)

{


echo $i;


$i++;



}


?>


While   Loop    Example    :

<?php
$a=5;
$i=1;
while($i<=10)
{
echo "  5*".$i."==".$a*$i.'<br>';
$i++;
}
?>
output  :
5*1==5
5*2==10
5*3==15
5*4==20
5*5==25
5*6==30
5*7==35
5*8==40
5*9==45
5*10==50



The PHP do...while Loop
The do...while loop will always execute the block of code once, it will then check the condition, and repeat the loop while the specified condition is true.


Do While  Loop  Concept:



Do while syntax:

Syntax

The syntax for do-while loop in JavaScript is as follows −
do{
   Statement(s) to be executed;
} while (expression);

Note − Don’t miss the semicolon used at the end of the do...while loop.


do

{
    code to be executed;
}

while (condition is true);

EXAMPLE   :

<?php

$i=0;
do
{





echo $i;

$i++;

}

while($i<5);



?>

Do-while    Loop   Example    :

<?php

$a=5;
$i=1;
do
{

echo "  5*".$i."==".$a*$i.'<br>';

$i++;

}

while($i<=10);

?>

Output   :

5*1==5
5*2==10
5*3==15
5*4==20
5*5==25
5*6==30
5*7==35
5*8==40
5*9==45
5*10==50



Simple Application for Practice use of  Loop:

(1)write  code for   table.html file:
<form action=”table.php”  method=”post”>
enter your number<input   type=”text”   name=”number”>
<input  type=submit    name=submit   value=submit>
</form>






(2)write  code for table.php  file:

<?php
$number=$_POST['number'];
for($i=1;$i<10;$i++)
{
echo  $number*$i.'<br>';

}


?>

output:


after click on submit button  you will get result.



==============================================================================================================================================

The PHP foreach Loop

The foreach loop works only on arrays, and is used to loop through each key/value pair in an array.

Syntax

foreach ($array as $value) {
    code to be executed;
}
Example:

<?php
$abc=array("apple","mango","orange");
foreach($abc  as $value)
{
echo "Current Fruits= $value".'<br>';

}

?>

output:

Current Fruits= apple
Current Fruits= mango
Current Fruits= orange

Example 2:
<?php
$abc=array("JILL"=>2439,"BOB"=>4986,"SAM"=>45689);
foreach($abc as  $key=>$value)
{
echo "key:".$key  ;
echo "value:".$value ."<br>";
}
?>

output:
key:JILL  value:2439
key:BOB  value:4986
key:SAM  value:45689


================================================================================================================================================

The each() function returns the current element key and value, and moves the internal pointer forward.
This element key and value is returned in an array with four elements. Two elements (1 and Value) for the element value, and two elements (0 and Key) for the element key.

Syntax

each(array)

ParameterDescription
arrayRequired. Specifies the array to use


<?php
$abc=array("JILL"=>2439,"BOB"=>4986,"SAM"=>45689);
while(list($key,$value)=each($abc))
{
echo "key:".$key  ;
echo "value:".$value ."<br>";
}
?>
output:

key:JILL value:2439
key:BOB  value:4986
key:SAM  value:45689
==============================================================================================================================================Nested For loop Examples :


<?php
$n=4;
for($i=0;$i<$n;$i++)
{

for($j=0;$j<$i;$j++)
{
 echo " 1";
}

echo "<br>";
}

?>

step 1: 
i=0  0<4   true
j=0  0<=0  true
print 1
j++
repeat j loop  
now j=1
1<=0  false
hence print 
 new line

 step 2:
 i=1  1<4  true
 j=0   0 <=1  true
 print 1
 j++
 repeat j loop
 now j=1

 1<=1  true
 print 1
 j++
 repeat j loop 
 now j=2
 2<=1 false
 new line

 step 3:
 i=2  2<4  true
 j=0  0<=1  true
 print 1
 j++
 repeat j loop  
 now j=1
 1<=2  true
 print 1
 j++
 repeat j loop
 now j=2
 2<=2  true
 print 1
 j++ 
 repeat j loop
 now j=3
 3<=2  false
 new line

 =======================================================================


<?php
echo "<h1>Multiplication table</h1>";
echo "<table border=2 width=50%"; 

for ($i = 1; $i <= 10; $i++ ) {   //this is the outer loop  ( used for row) 
  echo "<tr>";
  echo "<td>".$i."</td>";
  
   for ( $j = 2; $j <= 10; $j++ ) { // inner loop (used for column) 
        echo "<td>".$i * $j."</td>";
    }

   echo "</tr>";


echo "</table>"; 

?>

output:






========================================================================
Example of using the Continue statement :
========================================================================
<?php
echo "<p><b>Example of using the Continue statement:</b><p>";
for ($i=0; $i<=10; $i++) {
   if ($i==4){continue;}
   echo "The number is ".$i;
   echo "<br />";
}
?>

output:
Example of using the Continue statement:

The number is 0
The number is 1
The number is 2
The number is 3
The number is 5
The number is 6
The number is 7
The number is 8
The number is 9
The number is 10

========================================================================
Example of using the break statement :
========================================================================
<?php
echo "<p><b>Example of using the break statement:</b><p>";
for ($i=0; $i<=10; $i++) {
   if ($i==4){break;}
   echo "The number is ".$i;
   echo "<br />";
}
?>
output:

Example of using the break statement:
The number is 0
The number is 1
The number is 2
The number is 3

================================================================================================================================================
(1)Find all even numbers between 1 to 100 :

<?php

for ($i=2; $i<=100; $i+=2)

{
 
echo $i." ";

}

?>



Output :
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42
44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86
88 90 92 94 96 98 100
In the above example
Here loop starts from ($i=2 ) after every count $i increment its value by 2 and Print all even value from( 1 to 100)


(2)Find all odd numbers between 1 to 100 using loop :

<?php

for ($i=1; $i<=99; $i+=2)

{
 
echo $i." ";

}

?>
output:
1 3 5 7 9 … 99



(3)Find the Sum of even and odd numbers between 1 to 100:

<?php

for ($i=1; $i<=100; $i++)

{

if($i%2==0)

{
 
@$even=$even+$i;

}

else

{
 
@$odd=$odd+$i;

}


}

echo "Sum of even numbers=".$even."<br/>";

 echo "Sum of odd numbers=".$odd;

?>


Output :
Sum of even numbers=2550
Sum of odd numbers=2500
In the above example
For loop is used because we know how many times loop iterate. inside the for loop we declare if..else condition.

If( $%2==0) condition is true, then code will execute and calculate the sum of even number. otherwise else statement execute and calculate the sum of odd number.
Print the sum of odd ans even number separately.

Add two numbers using loop(Not use + operator):
<?php
               
$f=$_GET['f'];
               
$s=$_GET['s'];
               
for ($i=1; $i<=$s; $i++)
               
{
                 
 $f++;
               
}
                 
echo "Sum of given numbers=".$f;

?>

<body>
               
<form>
                 
 Enter first number <input type="text" name="f"><br/>

Enter Second number<input type="text" name="s"><br/>
                 
 <input type="submit" value="add">
               
</form>

 </body>



Subtract two numbers using loop(Not use – operator).


<?php
               
$f=$_GET['f'];
               
$s=$_GET['s'];
               
for ($i=1; $i<=$s; $i++)
               
{
                 
$f--;
               
}
                 
echo "Subtraction of given numbers=".$f;

?>

<html>

<body>
               
<form>
                 
Enter first number<input type="text" name="f"><br/>

Enter Second number<input type="text" name="s"><br/>
               
<input type="submit" value="Subtract">
               
</form>


<body>


without using strrev()  write code of php using for loop:




<?php

$string = "sandep";

$len = strlen($string);

for($i=$len; $i > 0; $i--)

{
    echo $string[$i-1];
}


?>


Create table using for loop in PHP


<?php

if(isset($_POST['create']))

{

$rows=$_POST['r'];

$cols=$_POST['c'];

echo "<table border='1'>";

for($i=0;$i<$rows;$i++)

{

echo "<tr>";

for($j=0;$j<$cols;$j++)

{

echo "<th>"."r".$i."c".$j."</th>";

}

echo "</tr>";

}

echo "</table>";

}

?>

<html>

<body>

<form method="post">

<table width="400" border="1">

<tr>

<td width="177">Enter number of rows </td>

<td width="207"><input type="text" name="r"/></td>

</tr>

<tr>

<td>Enter number of column </td>

<td><input type="text" name="c"/></td>

</tr>

<tr>

<td colspan="2">

<input type="submit" value="Create Table" name="create"/>

</td>

</tr>

</table>

</form>

</body>


</html>

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