Add startsWith()

README.md

@@ -195,7 +195,7 @@ S::standardize('fòô bàř'); // 'foo bar'
 
 ##### pad
 
-S::pad(string $str , int $length [, string $padStr [, string $padType [, string $encoding]]])
+S::pad(string $str , int $length [, string $padStr = ' ' [, string $padType = 'right' [, string $encoding ]]])
 
 Pads a string to a given length with another string. If length is less
 than or equal to the length of $str, then no padding takes places. The
@@ -208,7 +208,7 @@ S::pad('fòô bàř', 10, '¬ø', 'left', 'UTF-8'); // '¬ø¬fòô bàř'
 
 ##### padLeft
 
-S::padLeft(string $str , int $length [, string $padStr [, string $encoding]])
+S::padLeft(string $str , int $length [, string $padStr = ' ' [, string $encoding ]])
 
 Returns a new string of a given length such that the beginning of the
 string is padded. Alias for pad($str, $length, $padStr, 'left', $encoding)
@@ -219,7 +219,7 @@ S::padLeft('foo bar', 9, ' '); // '  foo bar'
 
 ##### padRight
 
-S::padRight(string $str , int $length [, string $padStr [, string $encoding]])
+S::padRight(string $str , int $length [, string $padStr = ' ' [, string $encoding ]])
 
 Returns a new string of a given length such that the end of the string is
 padded. Alias for pad($str, $length, $padStr, 'right', $encoding)
@@ -230,7 +230,7 @@ S::padRight('foo bar', 10, '_*'); // 'foo bar_*_'
 
 ##### padBoth
 
-S::padBoth(string $str , int $length [, string $padStr [, string $encoding]])
+S::padBoth(string $str , int $length [, string $padStr = ' ' [, string $encoding ]])
 
 Returns a new string of a given length such that both sides of the string
 string are padded. Alias for pad($str, $length, $padStr, 'both', $encoding)
@@ -239,14 +239,24 @@ string are padded. Alias for pad($str, $length, $padStr, 'both', $encoding)
 S::padBoth('foo bar', 9, ' '); // ' foo bar '
 ```
 
+##### startsWith
+
+S::startsWith(string $str, string $substring [, boolean $caseSensitive = true [, string $encoding ]])
+
+Returns true if the string $str begins with $substring, false otherwise.
+By default, the comparison is case-sensitive, but can be made insensitive
+by setting $caseSensitive to false.
+
+```php
+S::startsWith('foo bar', 'another', false, $encoding); // ' foo bar '
+```
+
 ## TODO
 
-**char** => chr
-
-**startsWith**
-
 **endsWith**
 
+**char** => chr
+
 **toSpaces**
 
 **toTabs**

src/Stringy/Stringy.php

@@ -365,6 +365,33 @@ class Stringy {
     public static function padBoth($str, $length, $padStr = ' ', $encoding = null) {
         return self::pad($str, $length, $padStr, 'both', $encoding);
     }
+
+    /**
+     * Returns true if the string $str begins with $substring, false otherwise.
+     * By default, the comparison is case-sensitive, but can be made insensitive
+     * by setting $caseSensitive to false.
+     *
+     * @param   string  $str            String to check the start of
+     * @param   string  $substring      The substring to look for
+     * @param   bool    $caseSensitive  Whether or not to enfore case-sensitivity
+     * @param   string  $encoding       The character encoding
+     * @return  bool    Whether or not $str starts with $substring
+     */
+    public static function startsWith($str, $substring, $caseSensitive = true,
+                                      $encoding = null) {
+        $encoding = $encoding ?: mb_internal_encoding();
+
+        $substringLength = mb_strlen($substring, $encoding);
+        $startOfStr = mb_substr($str, 0, $substringLength, $encoding);
+
+        if (!$caseSensitive) {
+            $substring = mb_strtolower($substring, $encoding);
+            $startOfStr = mb_strtolower($startOfStr, $encoding);
+        }
+
+        return $substring === $startOfStr;
+    }
+
 }
 
 ?>

tests/Stringy/StringyTest.php

@@ -390,6 +390,33 @@ class StringyTestCase extends PHPUnit_Framework_TestCase {
         return $testData;
     }
 
+    /**
+     * @dataProvider stringsForStartsWith
+     */
+    public function testStartsWith($expected, $string, $substring,
+                                $caseSensitive = true, $encoding = null) {
+        $result = S::startsWith($string, $substring, $caseSensitive, $encoding);
+        $this->assertEquals($expected, $result);
+    }
+
+    public function stringsForStartsWith() {
+        $testData = array(
+            array(true, 'foo bars', 'foo bar'),
+            array(true, 'FOO bars', 'foo bar', false),
+            array(true, 'FOO bars', 'foo BAR', false),
+            array(true, 'FÒÔ bàřs', 'fòô bàř', false, 'UTF-8'),
+            array(true, 'fòô bàřs', 'fòô BÀŘ', false, 'UTF-8'),
+            array(false, 'foo bar', 'bar'),
+            array(false, 'foo bar', 'foo bars'),
+            array(false, 'FOO bar', 'foo bars'),
+            array(false, 'FOO bars', 'foo BAR'),
+            array(false, 'FÒÔ bàřs', 'fòô bàř', true, 'UTF-8'),
+            array(false, 'fòô bàřs', 'fòô BÀŘ', true, 'UTF-8'),
+        );
+
+        return $testData;
+    }
+
 }
 
 ?>