Reorganize Samples

The samples have become unwieldy when running them from a browser. In particular, the drop-down lists are fixed size with no scrolling, and many of them are now just too large. I have moved all the Calculation samples up a level, and broken several categories (Basic, Chart, DateTime, Engineering, Financial, and Reader) into several pieces.

Convert-Online (now found in the Engineering category) had a number of different problems which are now resolved. It is the only member with any significant code change.

samples/DateTime2/SECOND.php

@@ -0,0 +1,48 @@
+<?php
+
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+
+require __DIR__ . '/../../Header.php';
+
+$category = 'Date/Time';
+$functionName = 'SECOND';
+$description = 'Returns the second of a time value. The second is given as an integer, ranging from 0 to 59';
+
+$helper->titles($category, $functionName, $description);
+
+// Create new PhpSpreadsheet object
+$spreadsheet = new Spreadsheet();
+$worksheet = $spreadsheet->getActiveSheet();
+
+// Add some data
+$testTimes = [
+    [0, 6, 0],
+    [1, 12, 15],
+    [3, 30, 12],
+    [5, 17, 31],
+    [8, 15, 45],
+    [12, 45, 11],
+    [14, 0, 30],
+    [17, 55, 50],
+    [19, 21, 8],
+    [21, 10, 10],
+    [23, 59, 59],
+];
+$testTimeCount = count($testTimes);
+
+$worksheet->fromArray($testTimes, null, 'A1', true);
+
+for ($row = 1; $row <= $testTimeCount; ++$row) {
+    $worksheet->setCellValue('D' . $row, '=TIME(A' . $row . ',B' . $row . ',C' . $row . ')');
+    $worksheet->setCellValue('E' . $row, '=D' . $row);
+    $worksheet->setCellValue('F' . $row, '=SECOND(D' . $row . ')');
+}
+$worksheet->getStyle('E1:E' . $testTimeCount)
+    ->getNumberFormat()
+    ->setFormatCode('hh:mm:ss');
+
+// Test the formulae
+for ($row = 1; $row <= $testTimeCount; ++$row) {
+    $helper->log(sprintf('(E%d): %s', $row, $worksheet->getCell('E' . $row)->getFormattedValue()));
+    $helper->log('Second is: ' . $worksheet->getCell('F' . $row)->getCalculatedValue());
+}