PHP Program to print n prime numbers

What is a Prime Number & Composite Number?

Prime numbers are natural numbers that are greater than 1 that are not a product of two smaller natural numbers.  Prime numbers are natural numbers that are greater than 1 that are not a product of two smaller natural numbers. Composite numbers are natural numbers greater than 1 and which are not prime numbers. For example, 7 has no divisors other than 1 and 7 itself which is a prime number and   has more than two divisors which is a composite number. 

How to n prime numbers using PHP?

In PHP to check whether the number is Prime by using Mod(%) Operator and if we get 0 except by 1 and the number itself, it won't be a prime number. In this program, we first have to accept the limit from the user and assign it to the variable and assign the value 0 into the variable ct and value 2 into the variable num. Then perform the while loop until the condition 'ct < n'  becomes false and in the block of the loop we have to assign the value 0 into the variable dCt. And then assign the value 2 into the variable i perform the for loop until the condition 'i <= num' becomes false and increment the value of the i in every iteration in the block of the loop we have to check the condition 'num % i == 0' if tru increment the value of the variable dCt. And after the completion of the for loop, we have to check the condition 'dCt == 1' if true print the value of the variable num and also increment the value of the variable ct and increment the value of the variable num.

ALGORITHM

Step 1: Accept the limit from the user and assign it to the variable n

Step 2: Assign the value 0 into the variable ct and value 2 into the variable num

Step 3: Perform the following Steps until the condition 'ct < n'  becomes false

Step 4: Assign the value 0 into the variable dCt

Step 5: Assign the value 2 into the variable i perform the following sub-step until the condition 'i <= num' becomes false and increment the value of the i in every iteration

        (i) Check the condition 'num % i == 0' if tru increment the value of the variable dCt

Step 6: Check the condition 'dCt == 1' if true print the value of the variable num and also increment the value of the variable ct

Step 7: Increment the value of the variable num

PHP Source Code

                                          <?php
$n = readline("Enter the limit of number required: ");
$ct = 0;
$num = 2;
while ($ct < $n) {
    $dCt = 0;
    for ($i = 2; $i <= $num; $i++) {
        if (($num % $i) == 0) {
            $dCt++;
        }
    }
    if ($dCt == 1) {
        echo $num . "  ";
        $ct++;
    }
    $num++;
}
?>
                                      

OUTPUT

Enter the limit of number required: 15
2  3  5  7  11  13  17  19  23  29  31  37  41  43  47