Cassidoo | Sheet Column lookup to get true column number from letter structure.

columnFinder.php

<?php

/*
  Solving Cassidoo's coding problem from the newsletter sent February 6th.

 	Co-Pilot assisted *sigh*

	I was on track to solve the problem, but co-pilot immediately spurted out the `pow`
	function before I had a chance to figure out the math. I'm not sure if I'm happy or
	annoyed. Co-Pilot is also helping me type this message out :|
 */

function getColumnNames() {
	return "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
}

function getLetterCount($letter) {

	return (strpos(getColumnNames(), strtoupper($letter)) + 1);
}

function getBase($column) {
	return pow(strlen(getColumnNames()), $column - 1);
}

function getColumnNumber($column) {
	$columnLength = strlen($column);
	$columnNumber = 0;

	for ($i = 0; $i < $columnLength; $i++) {
		$columnNumber += getLetterCount($column[$i]) * getBase($columnLength - $i);
	}

	return $columnNumber;
}

echo getColumnNumber("A") . PHP_EOL; // 1
echo getColumnNumber("AA") . PHP_EOL; // 27
echo getColumnNumber("AAZ") . PHP_EOL; // 728