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Defining and using (calling) a function

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• Using (= calling) an existing function
  • Syntax to call a function is:

    $var = funcName ( parameters ) ;

    Example 1:

    <?php $x = sin(1); print $x . "\n"; ?>

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  • Example Program: (Demo above code)                                                

    How to run the program:

    ssh -X netid@holland php /home/cs377001/PHP/intro-PHP/func1.php

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  • Example 2: test if a string is empty

    <?php $a = ""; $b = "abc"; if ( empty($a) ) { print("a is empty\n"); } else { print("a is not empty\n"); } if ( empty($b) ) { print("b is empty\n"); } else { print("b is not empty\n"); } ?>

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  • Example Program: (Demo above code)                                                

    How to run the program:

    ssh -X netid@holland php /home/cs377001/PHP/intro-PHP/func2.php

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• Defining Functions
  • Syntax to define a function in PHP:

    function funcName ( $param1 , $param2 , .... ) { statements }

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  • Example:

    function square( $x ) { $r = $x * $x ; return( $r ); }

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  • Using the defined function:

    $a = square( 4 );

    Example:

    <?php $a = square(4); print("Square of 4 = " . $a . "\n"); # Function definition function square( $x ) { $r = $x * $x ; return( $r ); } ?>

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  • Example Program: (Demo above code)                                                

    How to run the program:

    ssh -X netid@holland php /home/cs377001/PHP/intro-PHP/func2.php

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  • Note:

    The function definition can appear any where in the main program A function need not be defined before it is used...