Comparison operators on strings are usually case insensitive

Excel, Gnumeric and Google Spreadsheet are case insensitive, so the
default behavior of PHPExcel is modified accordingly.

However OpenOffice is case sensitive and is also supported via the
compatibility mode of PHPExcel.

Fixes #31

Classes/PHPExcel/Calculation.php

@@ -3557,15 +3557,37 @@ class PHPExcel_Calculation {
 		if (is_string($operand1) && $operand1 > '' && $operand1{0} == '"') { $operand1 = self::_unwrapResult($operand1); }
 		if (is_string($operand2) && $operand2 > '' && $operand2{0} == '"') { $operand2 = self::_unwrapResult($operand2); }
 
+		// Use case insensitive comparaison if not OpenOffice mode
+		if (PHPExcel_Calculation_Functions::getCompatibilityMode() != PHPExcel_Calculation_Functions::COMPATIBILITY_OPENOFFICE)
+		{
+			if (is_string($operand1)) {
+				$operand1 = strtoupper($operand1);
+			}
+
+			if (is_string($operand2)) {
+				$operand2 = strtoupper($operand2);
+			}
+		}
+
+		$useLowercaseFirstComparison = is_string($operand1) && is_string($operand2) && PHPExcel_Calculation_Functions::getCompatibilityMode() == PHPExcel_Calculation_Functions::COMPATIBILITY_OPENOFFICE;
+
 		//	execute the necessary operation
 		switch ($operation) {
 			//	Greater than
 			case '>':
-				$result = ($operand1 > $operand2);
+				if ($useLowercaseFirstComparison) {
+					$result = $this->strcmpLowercaseFirst($operand1, $operand2) > 0;
+				} else {
+					$result = ($operand1 > $operand2);
+				}
 				break;
 			//	Less than
 			case '<':
-				$result = ($operand1 < $operand2);
+				if ($useLowercaseFirstComparison) {
+					$result = $this->strcmpLowercaseFirst($operand1, $operand2) < 0;
+				} else {
+					$result = ($operand1 < $operand2);
+				}
 				break;
 			//	Equality
 			case '=':
@@ -3573,11 +3595,19 @@ class PHPExcel_Calculation {
 				break;
 			//	Greater than or equal
 			case '>=':
-				$result = ($operand1 >= $operand2);
+				if ($useLowercaseFirstComparison) {
+					$result = $this->strcmpLowercaseFirst($operand1, $operand2) >= 0;
+				} else {
+					$result = ($operand1 >= $operand2);
+				}
 				break;
 			//	Less than or equal
 			case '<=':
-				$result = ($operand1 <= $operand2);
+				if ($useLowercaseFirstComparison) {
+					$result = $this->strcmpLowercaseFirst($operand1, $operand2) <= 0;
+				} else {
+					$result = ($operand1 <= $operand2);
+				}
 				break;
 			//	Inequality
 			case '<>':
@@ -3592,6 +3622,21 @@ class PHPExcel_Calculation {
 		return TRUE;
 	}	//	function _executeBinaryComparisonOperation()
 
+	/**
+	 * Compare two strings in the same way as strcmp() except that lowercase come before uppercase letters
+	 * @param string $str1
+	 * @param string $str2
+	 * @return integer
+	 */
+	private function strcmpLowercaseFirst($str1, $str2)
+	{
+		$from = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
+		$to = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
+		$inversedStr1 = strtr($str1, $from, $to);
+		$inversedStr2 = strtr($str2, $from, $to);
+
+		return strcmp($inversedStr1, $inversedStr2);
+	}
 
 	private function _executeNumericBinaryOperation($cellID,$operand1,$operand2,$operation,$matrixFunction,&$stack) {
 		//	Validate the two operands

unitTests/Classes/PHPExcel/CalculationTest.php

@@ -0,0 +1,35 @@
+<?php
+
+require_once 'testDataFileIterator.php';
+
+class CalculationTest extends PHPUnit_Framework_TestCase
+{
+
+    public function setUp()
+    {
+        if (!defined('PHPEXCEL_ROOT')) {
+            define('PHPEXCEL_ROOT', APPLICATION_PATH . '/');
+        }
+        require_once(PHPEXCEL_ROOT . 'PHPExcel/Autoloader.php');
+    }
+
+    /**
+     * @dataProvider providerBinaryComparisonOperation
+     */
+    public function testBinaryComparisonOperation($formula, $expectedResultExcel, $expectedResultOpenOffice)
+    {
+        PHPExcel_Calculation_Functions::setCompatibilityMode(PHPExcel_Calculation_Functions::COMPATIBILITY_EXCEL);
+        $resultExcel = \PHPExcel_Calculation::getInstance()->_calculateFormulaValue($formula);
+        $this->assertEquals($expectedResultExcel, $resultExcel, 'should be Excel compatible');
+
+        PHPExcel_Calculation_Functions::setCompatibilityMode(PHPExcel_Calculation_Functions::COMPATIBILITY_OPENOFFICE);
+        $resultOpenOffice = \PHPExcel_Calculation::getInstance()->_calculateFormulaValue($formula);
+        $this->assertEquals($expectedResultOpenOffice, $resultOpenOffice, 'should be OpenOffice compatible');
+    }
+
+    public function providerBinaryComparisonOperation()
+    {
+        return new testDataFileIterator('rawTestData/CalculationBinaryComparisonOperation.data');
+    }
+
+}

unitTests/rawTestData/CalculationBinaryComparisonOperation.data

@@ -0,0 +1,53 @@
+# formula, expectedResultExcel, expectedResultOpenOffice
+'=TRUE',	TRUE,	TRUE
+'=1 + 2.5',	3.5,	3.5
+'=2.5 + 1',	3.5,	3.5
+'=1 - 2.5',	-1.5,	-1.5
+'=2.5 - 1',	1.5,	1.5
+'=3 > 1',	TRUE,	TRUE
+'=3 > 3',	FALSE,	FALSE
+'=1 > 3',	FALSE,	FALSE
+'=3 < 1',	FALSE,	FALSE
+'=3 < 3',	FALSE,	FALSE
+'=1 < 3',	TRUE,	TRUE
+'=3 = 1',	FALSE,	FALSE
+'=3 = 3',	TRUE,	TRUE
+'=1 = 1.0',	TRUE,	TRUE
+'=3 >= 1',	TRUE,	TRUE
+'=3 >= 3',	TRUE,	TRUE
+'=1 >= 3',	FALSE,	FALSE
+'=3 <= 1',	FALSE,	FALSE
+'=3 <= 3',	TRUE,	TRUE
+'=1 <= 3',	TRUE,	TRUE
+'=3 <> 1',	TRUE,	TRUE
+'=3 <> 3',	FALSE,	FALSE
+'=1 <> 1.0',	FALSE,	FALSE
+'="a" > "a"',	FALSE,	FALSE
+'="A" > "A"',	FALSE,	FALSE
+'="A" > "a"',	FALSE,	TRUE
+'="a" > "A"',	FALSE,	FALSE
+'="a" < "a"',	FALSE,	FALSE
+'="A" < "A"',	FALSE,	FALSE
+'="A" < "a"',	FALSE,	FALSE
+'="a" < "A"',	FALSE,	TRUE
+'="a" = "a"',	TRUE,	TRUE
+'="A" = "A"',	TRUE,	TRUE
+'="A" = "a"',	TRUE,	FALSE
+'="a" = "A"',	TRUE,	FALSE
+'="a" <= "a"',	TRUE,	TRUE
+'="A" <= "A"',	TRUE,	TRUE
+'="A" <= "a"',	TRUE,	FALSE
+'="a" <= "A"',	TRUE,	TRUE
+'="a" >= "a"',	TRUE,	TRUE
+'="A" >= "A"',	TRUE,	TRUE
+'="A" >= "a"',	TRUE,	TRUE
+'="a" >= "A"',	TRUE,	FALSE
+'="a" <> "a"',	FALSE,	FALSE
+'="A" <> "A"',	FALSE,	FALSE
+'="A" <> "a"',	FALSE,	TRUE
+'="a" <> "A"',	FALSE,	TRUE
+'="A" > "b"',	FALSE,	TRUE
+'="a" > "b"',	FALSE,	FALSE
+'="b" > "a"',	TRUE,	TRUE
+'="b" > "A"',	TRUE,	FALSE
+'="a2" > "a10"',	TRUE,	TRUE // Test natural sorting is not used