Program to Print Prime Number from 1 to 20
Prime number is a natural number greater than 1 or that can be divided exactly only by itself and 1. For instance: 2,3,5,7,11,13,17 and so on. Where 2 is even prime number and other than 2 are odd prime.
Given below is the program to print prime numbers upto 20.
<?php
echo "Print prime number series with For Loop.";
echo '<br>';
$number = 20;
for($i=1;$i<= $number ;$i++){
if( $i==1)
continue;
$flag= true;
for($j=2;$j < $i ;$j++){
if($i%$j ==0){
$flag= false;
break;
}
}
if($flag)
echo $i.' ';
}
echo '<br>';
echo '<br>';
echo '<br>';
echo 'Print prime numbers series with do while loop.';
echo '<br>';
$i=2;
do{
$flag = true;
$j=2;
do{
if($i%$j ==0 && $i!=2){
$flag= false;
break;
}
$j++;
}
while($j < $i);
if($flag){
echo $i.' ';
}
$i++;
}
while($i<=$number);
?>
Output
Print prime number series with For Loop.
2 3 5 7 11 13 17 19
Print prime numbers series with Do While loop.
2 3 5 7 11 13 17 19