PHP - Exemplo de operadores lógicos

Tente o exemplo a seguir para entender todos os operadores lógicos. Copie e cole o seguinte programa PHP no arquivo test.php e mantenha-o na raiz do documento do servidor PHP e navegue por ele usando qualquer navegador.

<html>
   
   <head>
      <title>Logical Operators</title>
   </head>
   
   <body>
      
      <?php
         $a = 42;
         $b = 0;
         
         if( $a && $b ) {
            echo "TEST1 : Both a and b are true<br/>";
         }else{
            echo "TEST1 : Either a or b is false<br/>";
         }
         
         if( $a and $b ) {
            echo "TEST2 : Both a and b are true<br/>";
         }else{
            echo "TEST2 : Either a or b is false<br/>";
         }
         
         if( $a || $b ) {
            echo "TEST3 : Either a or b is true<br/>";
         }else{
            echo "TEST3 : Both a and b are false<br/>";
         }
         
         if( $a or $b ) {
            echo "TEST4 : Either a or b is true<br/>";
         }else {
            echo "TEST4 : Both a and b are false<br/>";
         }
         
         $a = 10;
         $b = 20;
         
         if( $a ) {
            echo "TEST5 : a is true <br/>";
         }else {
            echo "TEST5 : a  is false<br/>";
         }
         
         if( $b ) {
            echo "TEST6 : b is true <br/>";
         }else {
            echo "TEST6 : b  is false<br/>";
         }
         
         if( !$a ) {
            echo "TEST7 : a is true <br/>";
         }else {
            echo "TEST7 : a  is false<br/>";
         }
         
         if( !$b ) {
            echo "TEST8 : b is true <br/>";
         }else {
            echo "TEST8 : b  is false<br/>";
         }
      ?>
      
   </body>
</html>

Isso produzirá o seguinte resultado -

TEST1 : Either a or b is false
TEST2 : Either a or b is false
TEST3 : Either a or b is true
TEST4 : Either a or b is true
TEST5 : a is true 
TEST6 : b is true 
TEST7 : a is false
TEST8 : b is false