Comparison of numerical strings (bug #23110)

git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@165552 c90b9560-bf6c-de11-be94-00142212c4b1

language/operators.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.77 $ -->
+<!-- $Revision: 1.78 $ -->
  <chapter id="language.operators">
   <title>Operators</title>
   <simpara>
@@ -461,6 +461,32 @@ echo "hallo" ^ "hello"; // Outputs the ascii values #0 #4 #0 #0 #0
      </tbody>
     </tgroup>
    </table>
+   <para>
+    If you compare integer with the string, the string is
+    <link linkend="language.types.string.conversion">converted to number</link>.
+    If you compare two numerical strings, they are compared as integers. These
+    rules are valid also for the
+    <link linkend="control-structures.switch">switch</link> statement.
+    <informalexample>
+     <programlisting role="php">
+<![CDATA[
+<?php
+var_dump(0 == "a"); // 0 == 0 -> true
+var_dump("1" == "01"); // 1 == 1 -> true
+
+switch ("a") {
+case 0:
+    echo "0";
+    break;
+case "a": // never reached because "a" is already matched with 0
+    echo "a";
+    break;
+}
+?>
+]]>
+     </programlisting>
+    </informalexample> 
+   </para>
    <para>
     Another conditional operator is the "?:" (or ternary) operator.
     <informalexample>