Add support for dropping XML declaration

README.md

@@ -394,6 +394,36 @@ will result in:
 <root><Good_guy><name>Luke Skywalker</name><weapon>Lightsaber</weapon></Good_guy><Bad_guy><name>Sauron</name><weapon>Evil Eye</weapon></Bad_guy></root>
 ```
 
+### Dropping XML declaration
+
+Call `$arrayToXml->dropXmlDeclaration()` method on ArrayToXml object to omit default XML declaration on top of the generated XML.
+
+Example:
+
+```php
+$root = [
+    'rootElementName' => 'soap:Envelope',
+    '_attributes' => [
+        'xmlns:soap' => 'http://www.w3.org/2003/05/soap-envelope/',
+    ],
+];
+$array = [
+    'soap:Header' => [],
+    'soap:Body' => [
+        'soap:key' => 'soap:value',
+    ],
+];
+$arrayToXml = new ArrayToXml($array, $root);
+
+$result = $arrayToXml->dropXmlDeclaration()->toXml();
+```
+
+This will result in:
+
+```xml
+<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope/"><soap:Header/><soap:Body><soap:key>soap:value</soap:key></soap:Body></soap:Envelope>
+```
+
 ## Testing
 
 ```bash

src/ArrayToXml.php

@@ -13,6 +13,8 @@ class ArrayToXml
 
     protected $replaceSpacesByUnderScoresInKeyNames = true;
 
+    protected $addXmlDeclaration = true;
+
     protected $numericTagNamePrefix = 'numeric_';
 
     public function __construct(
@@ -69,6 +71,10 @@ public static function convert(
 
     public function toXml(): string
     {
+        if ($this->addXmlDeclaration === false) {
+            return $this->document->saveXml($this->document->documentElement);
+        }
+
         return $this->document->saveXML();
     }
 
@@ -105,6 +111,13 @@ public function prettify()
         return $this;
     }
 
+    public function dropXmlDeclaration()
+    {
+        $this->addXmlDeclaration = false;
+
+        return $this;
+    }
+
     private function convertElement(DOMElement $element, $value)
     {
         $sequential = $this->isArrayAllKeySequential($value);

tests/ArrayToXmlTest.php

@@ -453,4 +453,24 @@ public function it_can_set_dom_properties()
         $this->assertTrue($dom->formatOutput);
         $this->assertEquals('1234567', $dom->version);
     }
+
+    /** @test */
+    public function it_can_drop_xml_declaration()
+    {
+        $root = [
+            'rootElementName' => 'soap:Envelope',
+            '_attributes' => [
+                'xmlns:soap' => 'http://www.w3.org/2003/05/soap-envelope/',
+            ],
+        ];
+        $array = [
+            'soap:Header' => [],
+            'soap:Body' => [
+                'soap:key' => 'soap:value',
+            ],
+        ];
+        $arrayToXml = new ArrayToXml($array, $root);
+
+        $this->assertMatchesSnapshot($arrayToXml->dropXmlDeclaration()->toXml());
+    }
 }

tests/__snapshots__/ArrayToXmlTest__it_can_drop_xml_declaration__1.php

@@ -0,0 +1,3 @@
+<?php
+
+return '<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope/"><soap:Header/><soap:Body><soap:key>soap:value</soap:key></soap:Body></soap:Envelope>';