PHP Program to Convert a Given Number to Words
Given an integer N, the task is to convert the given number into words using PHP.
Examples:
Input: N = 438237764
Output: Four Hundred Thirty Eight Million Two Hundred Thirty Seven Thousand Seven Hundred Sixty Four
Input: N = 1000
Output: One Thousand
Below are the approaches to convert a given number to words:
Using a Pre-defined Array of Words
In this method we use pre-defined arrays containing words for units, tens, and special cases like numbers 11-19. It processes the given number by breaking it down into its individual digits and constructs the word representation by concatenating the corresponding words from the arrays.
Example: Below is the implementation of the above approach to convert a given number to words.
<?php
function numToWords($number) {
$units = array('', 'one', 'two', 'three', 'four',
'five', 'six', 'seven', 'eight', 'nine');
$tens = array('', 'ten', 'twenty', 'thirty', 'forty',
'fifty', 'sixty', 'seventy', 'eighty',
'ninety');
$special = array('eleven', 'twelve', 'thirteen',
'fourteen', 'fifteen', 'sixteen',
'seventeen', 'eighteen', 'nineteen');
$words = '';
if ($number < 10) {
$words .= $units[$number];
} elseif ($number < 20) {
$words .= $special[$number - 11];
} else {
$words .= $tens[(int)($number / 10)] . ' '
. $units[$number % 10];
}
return $words;
}
// Example usage:
$number = 90;
echo "Number $number in words: "
. numToWords($number);
?>
Output
Number 90 in words: ninety
Time Complexity: O(Log10(N))
Auxiliary Space: O(1)
Using Recursive Function for Large Numbers
In this approach we use recursive function to handle larger numbers by breaking them down into smaller parts, such as hundreds, thousands, or millions, and recursively converting each part into words.
Example: Below is the implementation of the above approach to convert a given number to words
<?php
function numToWordsRec($number) {
$words = array(
0 => 'zero', 1 => 'one', 2 => 'two',
3 => 'three', 4 => 'four', 5 => 'five',
6 => 'six', 7 => 'seven', 8 => 'eight',
9 => 'nine', 10 => 'ten', 11 => 'eleven',
12 => 'twelve', 13 => 'thirteen',
14 => 'fourteen', 15 => 'fifteen',
16 => 'sixteen', 17 => 'seventeen', 18 => 'eighteen',
19 => 'nineteen', 20 => 'twenty', 30 => 'thirty',
40 => 'forty', 50 => 'fifty', 60 => 'sixty',
70 => 'seventy', 80 => 'eighty',
90 => 'ninety'
);
if ($number < 20) {
return $words[$number];
}
if ($number < 100) {
return $words[10 * floor($number / 10)] .
' ' . $words[$number % 10];
}
if ($number < 1000) {
return $words[floor($number / 100)] . ' hundred '
. numToWordsRec($number % 100);
}
if ($number < 1000000) {
return numToWordsRec(floor($number / 1000)) .
' thousand ' . numToWordsRec($number % 1000);
}
return numToWordsRec(floor($number / 1000000)) .
' million ' . numToWordsRec($number % 1000000);
}
// Example usage:
$number = 1234567;
echo "Number $number in words: "
. numToWordsRec($number);
?>
Output
Number 1234567 in words: one million two hundred thirty four thousand five hundred sixty seven
Time Complexity: O(Log N)
Auxiliary Space: O(Log N)
