Tutorial: Introduction To PHP Part I

Dr. Thomas E. Hicks
Computer Science Department
Trinity University

3]  <SCRIPT LANGUAGE = "php". ........ <SCRIPT>

2]  Double Dynamic data-typing

    $PayPerHour = 15.75;

3]  String Dynamic data-typing

    $Name = "Tom";

1] + Addition ==> X$ = 2 + 3;  // $X = 5

4] + Division ==> X$ = 15 / 3;  // $X = 5

6]  X$ = 2  += ==> X$ += 3;  // $X = 5

7]  X$ = 2  *= ==> X$ *= 3;  // $X = 6

8]  X$ = 2  -= ==> X$ -= 3;  // $X = -1

9]  X$ = 8  /= ==> X$ /= 2;  // $X = 4

10]  X$ = 7  %= ==> X$ %= 3;  // $X = 1

2]  != Non-Equivalence ==> if ($X != 5) ... true/false

3]  > Greater Than ==> if ($X > 5) ... true/false

5]   >= Greater Than Or Equal To ==> if ($X >= 5) ... true/false

6]   <= Less Than Or Equal To ==> if ($X <= 5) ... true/false

9]   !    NOT ==> if (! $X) ... true/false

<?PHP
$FacultyNo = 2;
If ($FacultyNo == 1)
   Print ("<H1>Eggen</H1>");
Else
   Print ("<H1>Not Eggen</H1>");
?>

2 ] Like C/C++, one need not include braces to bind a single statement.

<?PHP
$FacultyNo = 1;
If ($FacultyNo == 1)
   Print ("<H1>Eggen</H1>");
Else
   Print ("<H1>Not Eggen</H1>");
   Print ("<H1>Might Be Hicks!</H1>");
?>

2] Since there are no braces around the two print statements in the else clause, only the first is associated with the conditional statement.

Function BigGreetings()
{
   Print ("<H1><CENTER> Greetings From Trinity University </CENTER></H1>");
}

2] The function is called with the line

         BigGreetings( );

<?PHP
Function BigGreetings()
{
Print ("<H1><CENTER> Greetings From Trinity University </CENTER></H1>");
}

BigGreetings();
?>

<HR><CENTER> Separator </CENTER><HR>

<?PHP
BigGreetings();
?>

4] I recommend placing all functions at the top of the page. They may be called where needed. (See Below!)

1] Write the PHP code for a function, called Square( ) which will display the square of the passed numerical value centered in the biggest and boldest font one to a line. Assume that this is the the portion of the page which evokes/calls your Square function. Assume the following code to evoke/call your function.
 

<?PHP
For ($Pos = 5; $Pos >= 1; $Pos --)
{
   Square($Pos);
}
?>

2] The function is called with the line

         Square($Pos);

3] The Code For The Square function.

Function Square($No)
{
   Print ("<H1><CENTER>");
   Print ($No * $No);
   Print ("</CENTER></H1>");
}

4] Putting it all together:   (See Below!)
 

5] I recommend placing all functions at the top of the page. They may be called where needed. (See Below!)

1] Write the PHP code for a function, called Sum ( ) which will explicitly return the sum of the two passed numerical arguments. Assume the following code to evoke/call your function.

<?PHP
For ($Pos = 1; $Pos <= 9; $Pos ++)
{
   Print ("<BR> 2 + ");
   Print ($Pos);
   Print (" = ");
   Print Sum(2, $Pos);
}
?>

2] The function is called with

         Sum(2, $Pos)

3] The Code For The Sum function.

Function Sum($No1, $No2)
{
   $ReturnValue = $No1 + $No2;
   return ($ReturnValue);
}

4] Putting it all together: (See Below!)  Variables declared within a function are local/available only within that function.
 

5] I recommend placing all functions at the top of the page. They may be called where needed. (See Below!)

2]Variable $No1 is not local to any function. It is a Global, On Demand, Variable. Any function, that includes the global statement Global $No1; shall have access to the contents of $No1. (See Below!)

<?PHP
$No1 = 2;
Function Sum($No2)
{
Global $No1;

   $ReturnValue = $No1 + $No2;
   return ($ReturnValue);
}
?>

<?PHP
For ($Pos = 1; $Pos <= 9; $Pos ++)
{
   Print ("<BR> ");
   Print ($No1);
   Print (" + ");
   Print ($Pos);
   Print (" = ");
   Print Sum($Pos);
}
?>

<?PHP
$Names = Array ("Tom", "Dick", "Harry");

For ($Pos = 0; $Pos <= 2; $Pos ++)
{
   Print ($Names[$Pos]);
   Print ("<BR> ");
}
Print ("<P> No Elements In Array Names = ");
Print (Count($Names));
?>

2] The array subscripting begins with element 0. The Count function explicitly returns the number of elements in the array.

<?PHP
$Names[4] = "Ann";
$Names[2] = "Sally";
$Names[17] = "Judy";


ForEach ($Names As $Name)
{
   Print ($Name);
   Print ("<BR> ");
}
Print ("<P> No Elements In Array Names = ");
Print (Count($Names));
?>

2] As you can see, the array subscripts need not be sequential. When using the ForEach statement, they are rendered in exactly the same order in which they are filled.

1] Write the Output from the following PHP code.

<?PHP
$Names[1] = "Ann";
$Names[2] = "Sally";
$Names[0] = "Judy";


For ($Pos = 0; $Pos <= 2; $Pos ++)
{
   Print ($Names[$Pos]);
   Print ("<BR> ");
}
Print ("<P> No Elements In Array Names = ");
Print (Count($Names));
?>

2] When consecutive subscripts are used, the for loop will output data in sequential order.

<?PHP
$Names[0] = "Tom";
$Names[1] = "Hicks";
$Names[2] = "999-7483";
$Names[3] = "Male";
$Names[4] = 50;
$Names[5] = true;


For ($Pos = 0; $Pos <= 5; $Pos ++)
{
   Print ($Names[$Pos]);
   Print ("<BR> ");
}
Print ("<BR> No Elements In Array Names = ");
Print (Count($Names));
?>

2] Just as normal variables utilize dynamic data-typing, each element in the array also can accept dynamic data-typing.

1] Write a block of code that demonstrates the built in Array_Merge Utility.

<?PHP
$Array1 = Array ("Tom", "Dick", "Harry");
$Array2 = Array (1, 2, 3);
$Array3 = Array_Merge($Array1, $Array2);

For ($Pos = 0; $Pos < Count($Array3); $Pos ++)
Print ("<BR> $Array3[$Pos]");
?>

2] PHP pages have the extension .php

3] As a middleware scripting language, PHP co-exists with HTML scripting; it was designed for Web Programmers.

4] PHP has built-in support for a large collection of databases.

5] PHP is much faster than Perl and CGI alternatives.

6] PHP is open source. It is well maintained and portable.