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 6 has more than two divisors which is a composite number.
For example, 2, 3, 5, 7, 11, 13, etc are prime numbers because they have only 2 divisors and the number '4', '6', which have more than two divisors are composite numbers.
Let us take an example as the number '5' is a prime number because the number '5' has only two divisors: '1' and '5'. So the prime number has two divisors only. But, 4 is not prime (it is composite) since 2 x 2 = 4.
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 n 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.
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
$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++;
}
?>
Enter the limit of number required: 15 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47
