﻿ PHP Function Exercise: Check whether a number is prime or not - w3resource

# PHP function Exercises: Check whether a number is prime or not

## PHP function: Exercise-2 with Solution

Write a PHP function to check whether a number is prime or not.

Note: A prime number (or a prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself.

Visual Presentation:

Sample Solution:

PHP Code:

``````<?php
// Function to check if a number is prime
function IsPrime(\$n)
{
// Loop through all numbers from 2 to n-1
for (\$x = 2; \$x < \$n; \$x++)
{
// If n is divisible by any number other than 1 and itself,
// it's not prime, so return 0
if (\$n % \$x == 0)
{
return 0;
}
}
// If no divisor found, n is prime, so return 1
return 1;
}

// Call the IsPrime function to check if 3 is prime
\$a = IsPrime(3);

// Check the return value and print the result
if (\$a == 0)
echo 'This is not a Prime Number.....' . "\n";
else
echo 'This is a Prime Number..' . "\n";
?>
```
```

Output:

```This is a Prime Number..
```

Explanation:

In the exercise above,

• Define a function named "IsPrime()" which takes an integer parameter '\$n'.
• Inside the function, there's a loop that iterates from 2 to one less than '\$n'. This loop checks for divisors of '\$n'.
• If '\$n' is divisible by any number other than 1 and itself, the function returns 0, indicating that the number is not prime.
• If no divisor is found in the loop, the function returns 1, indicating that the number is prime.
• Outside the function, the "IsPrime()" function is called with an argument of 3, and the result is stored in the variable '\$a'.
• The code then checks the value of '\$a' and prints whether 3 is a prime number or not.

Flowchart :

PHP Code Editor:

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