PHP, Structures and Functions, Fundamental Syntaxes

switch

Behavior similar to if ... elseif ... else.

Is a very important language construction, because it allows decision making during the programming process.

Of course, there are other implementations - more complex and specific - for conditional evaluation.

Right now, what we teach you is enough.

We shall certainly return to the matter soon.

FIRST SYNTAX TYPE

In the following, we will show the FIRST SYNTAX TYPE of - switch - conditional structure:


<?php

// STRUCTURE #1

switch (var)
    {
    case val 1:
    statement 1
    break;
    
    case val 2:
    statement 2
    break;
    
. . . . . . . . . . . .

    case val J:
    statement J
    break;
    
. . . . . . . . . . . .

    default:
    default statement
    }

?>

Each of the case structures are evaluated according to a BOOLEAN type.

01 . statement 1 will be executed...

      If the case val 1: is verified as TRUE

02 . statement 2 executed...

      If case val 1: is verified as FALSE.

03 . statement 3 executed...

      If case val 1: is verified as FALSE
and
          case val 2: is verified as FALSE.

04 . statement 3 executed...

      If case val 1: is verified as FALSE
and
          case val 2: is verified as FALSE
and
          case val 3: is verified as FALSE.

And so on...

If all case val X: are evaluated as FALSE, then the default statement will be executed.

0N . default statement executed...

default: always TRUE.

SECOND SYNTAX TYPE

In the following, we will show the SECOND SYNTAX TYPE of - switch - conditional structure:


<?php

// STRUCTURE #2

switch (var):

    case val 1:
    statement 1
    break;
    
    case val 2:
    statement 2
    break;
    
. . . . . . . . . . . .

    case val J:
    statement J
    break;
    
. . . . . . . . . . . .

    default:
    default statement
    
    endswitch;

?>

THIRD SYNTAX TYPE

In the following, we will show the THIRD SYNTAX TYPE of - switch - conditional structure:


<?php

// STRUCTURE #3

switch (var)
    {
    case val 1;
    case val 2;
    case val 3;
    . . . . . . . .
    case val J;
    . . . . . . . .
    statement 123
    break;
    
    default:
    default statement
    break;
    }

?>

Each of the case structures are evaluated according to a BOOLEAN type.

01 . statement 1 will be executed ...

      If case val 1 is TRUE
    OR
            case val 2 is TRUE
    OR
               case val 3 is TRUE
              . . . . . . . . . . . . . . . . . . . .
    OR
               case val J is TRUE

0N . default statement will be executed ...

      If all previous case val 1, val2, ... etc. are evaluated as FALSE.

SOLVE ALL PROPOSED EXERCISES

NOT SOLVED YET

If possible in several versions of PHP

Especially the latest 7 and 8

Study the displayed data carefully

EXERCISE


<?php

/* - - - - - - - - - - - - - - - - - - - - - - -

   Data collected by some input process 
   in the variable $d01
   
   - - - - - - - - - - - - - - - - - - - - - - - */

$d01 = 'Isaac Newton';

switch ($d01)

{
case 'Socrates':
echo $d01 . ', the philosopher!';
break;

case 'Isaac Newton':
echo $d01 . ', the physicist!';
break;

case 'Mariah Carey':
echo $d01 . ', the singer!';
break;

default:
echo 'Not related!';
}

?>

RESULT

Isaac Newton, the physicist!

EXERCISE


<?php

/* - - - - - - - - - - - - - - - - - - - - - - -

   Data collected by some input process 
   in the variable $d02
   
   - - - - - - - - - - - - - - - - - - - - - - - */

$d02 = 'Socrates';

switch ($d02):

case 'Socrates':
echo $d02 . ', the philosopher!';
break;

case 'Isaac Newton':
echo $d02 . ', the physicist!';
break;

case 'Mariah Carey':
echo $d02 . ', the singer!';
break;

default:
echo 'Not related!';

endswitch;

?>

RESULT

Socrates, the philosopher!

EXERCISE


<?php

/* - - - - - - - - - - - - - - - - - - - - - - -

   Data collected by some input process 
   in the variable $d03
   
   - - - - - - - - - - - - - - - - - - - - - - - */

$d03 = 'Mariah Carey';

switch ($d03)
{
case 'Socrates';
case 'Isaac Newton';
case 'Mariah Carey';
echo $d03 . ', Is related!';
break;

default:
echo 'Not related!';
}

?>

EXERCISE


<?php

/* - - - - - - - - - - - - - - - - - - - - - - -

   Data collected by some input process 
   in the variable $d04
   
   - - - - - - - - - - - - - - - - - - - - - - - */

$d04 = 'Red';

switch ($d04):

case 'Red';
case 'Green';
case 'Blue';
echo $d04 . ', Is related!';
break;

default:
echo 'Not related!';

endswitch;

?>