PHP Exercises: Check whether a number is an Armstrong number or not

PHP: Exercise-32 with Solution

Write a PHP program to check whether a number is an Armstrong number or not. Return true if the number is Armstrong otherwise return false.

An Armstrong number of three digits is an integer so that the sum of the cubes of its digits is equal to the number itself. For example, 153 is an Armstrong number since 1**3 + 5**3 + 3**3 = 153

Sample Solution: -

PHP Code:

function armstrong_number($num) {
  $sl = strlen($num);
  $sum = 0;
  $num = (string)$num;
  for ($i = 0; $i < $sl; $i++) {
    $sum = $sum + pow((string)$num{$i},$sl);
  if ((string)$sum == (string)$num) {
    return "True";
  } else {
    return "False";
echo "Is 153 Armstrong number? ".armstrong_number(153);
echo "\nIs 21 Armstrong number? ".armstrong_number(21);
echo "\nIs 4587 Armstrong number? ".armstrong_number(4587);"\n";

Sample Output:

Is 153 Armstrong number? True                                          
Is 21 Armstrong number? False                                          
Is 4587 Armstrong number? False 


Flowchart: Check whether a number is an Armstrong number or not

PHP Code Editor:

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PHP: Tips of the Day

Why shouldn't I use mysql_* functions in PHP?

The MySQL extension:

  • Is not under active development
  • Is officially deprecated as of PHP 5.5 (released June 2013).
  • Has been removed entirely as of PHP 7.0 (released December 2015)
  • This means that as of 31 Dec 2018 it does not exist in any supported version of PHP. If you are using a version of PHP which supports it, you are using a version which doesn't get security problems fixed.
  • Lacks an OO interface
  • Doesn't support:
    • Non-blocking, asynchronous queries
    • Prepared statements or parameterized queries
    • Stored procedures
    • Multiple Statements
    • Transactions
    • The "new" password authentication method (on by default in MySQL 5.6; required in 5.7)
    • Any of the new functionality in MySQL 5.1 or later

Since it is deprecated, using it makes your code less future proof.

Lack of support for prepared statements is particularly important as they provide a clearer, less error-prone method of escaping and quoting external data than manually escaping it with a separate function call.

Ref : https://bit.ly/2BIIsF0