Lesson 1
Remember to end every instruction with a semicolon ;
Special note. In order to display bits of code additional spaces have been inserted into some commands so they render as text. Look at the source code for the real stuff.
Page 7 – “Today is < ? php echo date(‘j F Y’); ? >”
Today is 12 January 2011
Page 8 -
The time is < ?php echo date(‘H:i:s’);?>
and the date is < ?php echo date(‘j F Y’);?>
The time is 22:58:26 and the date is 12 January 2011
Comment styles
Single line can be either // or #
Multiple line starts with /* and ends with */
Commenting a script
< ?php /* Time.php – or whatever your php page s called.
This script prints the current date
and time in the web browser.
*/
echo ‘The time is ‘;
echo date(‘H:i:s’); //Hours minutes & seconds
echo ‘and the date is ‘
echo date(‘j F Y’); #day, month and year
?>
The time is 22:58:26and the date is 12 January 2011
Lesson 2 – variables
Variables are always prefixed with a dollar ($) sign and start with a letter or underscore (used by ‘system’ variable. They do not need to be declared. They are case sensitive.
e.g. $FirstName, $_POST
Use ‘=’ to assign a variable to a value or an expression
$total = 2 * 8;
$FirstName = “Bob”;
Using variables in strings
A variable in a double quoted string uses its value.
A variable in a single quoted string uses its name.
< ?php $FirstName = “Bob”;
echo “Hello, $FirstName < br >”;
echo ‘Hello, $FirstName < br >’;
?>
Hello, Bob
Hello, $FirstName
You may need to delimit a variable, do this with braces {}.
< ?php $weight = 125 echo “The weight is {$weight}gms < br >” ? >
The weight is 125gms
Joining/ concatenating strings
Use the period to indicate concatenation.
< ?php
echo “The weight is “. $weight.”gms< br >”;
? >
The weight is 125gms
You can extend this to build a long string
< ?php
$mystring = “The weight is “;
$mystring .= $weight;
$mystring .= “gms< br >”;
echo $mystring;
? >
The weight is 125gms
Indirects or Variable Variables.
You can use the value of one variable to redirect to another variable.
< ?php
$weight = 125;
$name=”weight”;
echo “The value of the variable called ‘$name’ is ${$name} “;
?>
The value of the variable called ‘weight’ is 125
Lesson 3 – flow control
From here on we will assume the <?php tags in the descriptive text.
Conditional evaluations
| $test=5; |
#set a value |
| if ($test < 10) |
# (test is inside round brackets) |
{
echo “a is less than 10″;
} |
# Execute code inside {} if TRUE |
| elseif ($test == 10) |
# if first test fails, then try this one
Note the comparison operator, see list below. |
{
echo “a is equal to 10″;
} |
# Execute code inside {} if second test is TRUE |
| else |
# otherwise |
{
echo “a is greater than 10″;
} |
# execute this code |
a is less than 10
Comparison operators
| Operator |
What it does |
| == |
is equal to |
| === |
is equal to AND same data type |
| != |
NOT equal to |
| !== |
NOT equal to AND same data type |
| < |
Less than |
| <= |
Less than or equal to |
| > |
Greater than |
| >= |
Greater than or equal to |
Logical operators (in order of evaluation)
| Operator |
What it does |
| !a |
NOT – TRUE if a is NOT TRUE |
| a && b |
AND – TRUE if both a AND b are TRUE |
| a || b |
OR – TRUE if either a OR b are TRUE |
| a and b |
AND – TRUE if both a AND b are TRUE |
| a xor b |
XOR – TRUE if either a OR b are TRUE, but NOT both |
| a or b |
OR – TRUE if either a OR b are TRUE |
“switch” statement
Use this when making several clear comparisons, especially from a list.
| $result=”Great”; |
# set up the comparison value |
| switch ($result) { |
# show which variable is being used |
case “Average”:
case “Good”: |
# either of these will trigger this condition |
| echo “You scored between 10 and 20 points.<br>”; |
|
| break; |
# make sure you skip all other code within the switch command |
| case “Great”: |
# next comparison |
echo “You scored between 21 and 28 points.<br>”;
break; |
|
case “Superb”:
echo “You scored over 28 points.<br>”;
break; |
|
default:
echo “You scored less than 10 points.<br>”;
} |
# if all else fails |
You scored between 21 and 28 points.
Loops
There are three types of loops:-
WHILE
| Code |
Note |
| $count = 1; |
# Initialise (assign) the loop variable |
| while ($count <= 10) { |
# set up the WHILE condition |
| $square = $count * $count; |
# Do the code within the {} for each iteration |
| echo “$count squared is $square <br>”; |
|
| $count++; |
# Alter the loop counter |
| } |
|
1 squared is 1
2 squared is 4
3 squared is 9
4 squared is 16
5 squared is 25
6 squared is 36
7 squared is 49
8 squared is 64
9 squared is 81
10 squared is 100
DO
| Code |
Note |
| $count = 1; |
# Initialise (assign) the loop variable |
| do { |
# Do the loop at least once |
| $square = $count * $count; |
# Do the code within the {} for each iteration |
| echo “$count squared is $square <br>”; |
|
| $count++; |
# Alter the loop counter |
| }while ($count <= 10) |
# test the WHILE condition |
1 squared is 1
2 squared is 4
3 squared is 9
4 squared is 16
5 squared is 25
6 squared is 36
7 squared is 49
8 squared is 64
9 squared is 81
10 squared is 100
FOR
Works like WHILE
| Code |
Note |
| for ($count = 1; $count <= 10; $count++) |
# set FOR parameters
# Initial value; final value; method of altering test variable at the end of each loop |
| { |
|
$square = $count * $count;
echo “$count squared is $square <br>”; |
# Do the code within the {} for each iteration |
| } |
|
1 squared is 1
2 squared is 4
3 squared is 9
4 squared is 16
5 squared is 25
6 squared is 36
7 squared is 49
8 squared is 64
9 squared is 81
10 squared is 100
Breaking out of loops
Use BREAK; to end the iterations and continue from the next instruction or use CONTINUE; to stop this iteration and run the next one.
Lesson 4 – Functions
Use functions for repetitive or reusable tasks
Define a function
A function to calculate VAT.
| Code |
Note |
| function VAT($xmount) { |
# Name of function and (arguments) |
| $VAT=$xmount * 0.175; |
# work out the result |
| return $VAT; |
# this is the value sent back |
| } |
|
The price is 25
and the VAT is 4.38
giving a total of 29.38
Mail function & return values
| Code |
Note |
| if (mail(“tony.lord@peoplefirst.co.uk”,”Hello”,”Test mail from the php page”,”from: pfs.php@peoplefirst.co.uk”)) { |
# mail is a built in function with arguments (destination, titles, message) |
|
# and returns TRUE (1) if mail sent and FALSE (0) if not |
| echo “Email successful”; } |
|
| else |
|
| { echo “Email not sent”; } |
|
Email successful
Lesson 5 – numbers & maths
Increment and decrement
No = 1 = 1
No inc, then print = 2 ++$x
No print then inc = 2 $x++
Print No = 3 3
No dec then print = 2 –$x
No inc by 5 & print = 7 ($x +=5)
Note the brackets round compound expressions in strings.
Shortcuts/ Compound operators
x = 2 = 2
y = 5 = 5
Add, then print = 7 ($x += $y)
Subtract, then print = -3 ($x -= $y)
Same for * and /
Percent, then print = 2 ($x %= $y) (maybe works in php 5?)
Rounding numbers
The starting number is = 3.1415927.
Rounding up, answer = 4 uses function ceil($x)
Rounding down, answer = 3 uses function floor($x)
The starting number is = -3.1415927.
Rounding up, answer = -3 uses function ceil($x)
Rounding down, answer = -4 uses function floor($x)
The starting number is = 3.1415927.
Standard Rounding, answer = 3.14 uses function round($x,2)
The starting number is = 3.147.
Standard Rounding, answer = 3.15 uses function round($x,2)
Random numbers
This random integer is between 3 and 100 and is 57 using function rand($x,$y).
This random integer is between 3 and 100 and is 42 using function rand($x,$y).
This random integer is between 3 and 100 and is 86 using function rand($x,$y).
The highest random integer is and is found in the constant $RAND_MAX. (PHP 5?)
Lesson 6 – strings
For a full list of string functions see http://www.php.net/manual/en/ref.strings.php
String examples
This is a string example – ‘This is a string example’
This is a string example – “This is a string example”
This is a “string” example – This is a \”string\” example including escaped quote marks
Using variables – a $ in a double quoted string looks for the variable value,
within a single quoted string uses the literal.
Concatenating this ( $a = This is part one ) and this ( $b = and this is part two )
gives – This is part one and this is part two – using $a . $b
Compare strings using $a == $b for equality (N.B. case sensitive)
Compare strings using $a > $b (or <, >=, <=) for ASCII code values (N.B. case sensitive)
Formatting Strings
printf function gives simple formatting printing.
The boat has the number 4094 and a price of 2345.670000.
printf(“The %s has the number %d and a price of %f.” , $item , $number, $price );
where %s is a string variable, %d a decimal and %f a floating point one.
The order of the specified variables in the string corresponds to their position in the parameter section.
Format characters available for printf
| Character |
Meaning |
| b |
Binary number |
| c |
Ascii character code |
| d |
Signed decimal integer |
| e |
Scientific notation |
| f |
Floating point |
| o |
Octal |
| s |
String |
| u |
Unsigned decimal integer |
| x |
Hex (lower case) |
| X |
Hex (UPPER CASE) |
The boat has the number 4094 and a price of 2345.
printf(“The %s has the number %d and a price of %d.” , $item , $number, $price );
where %s is a string variable, %d are both decimal.
Alignment – padding
echo “< PRE >”;
printf (“%10s , %s \n”,$first,$second); right align 10 spaces
printf (“%-10s , %s”, $third, $fourth); left align 10 spaces
echo “< /PRE >”;
First , Second
Third , Fourth
Alignment – numbers
The price is 002345.67
printf (“The price is %09.2f”,$price);
The ’0′ after the ‘%’ is the fill character,
the ’9′ is the total length and
the 2 is the number of digits after the decimal point.
Formatted variables
The price is 002345.67
$formatprice = sprintf (“The price is %09.2f”,$price);
echo $formatprice
Capitalisation
$string = I love SailinG
I LOVE SAILING - strtoupper ($string)
i love sailing - strtolower ($string)
I love SailinG - ucfirst ($string)
I Love SailinG - ucwords ($string)
I Love Sailing - ucwords (strtolower ($string))
Substrings
i love SailinG
ove S – select part of string (Starts at 0) – echo substr ($string,3,5)
inG – Selct from end – substr ($string,-3)
14 – Length of string – strlen($string)
4 – find “v” in string – strpos ($string, “v”)
ve SailinG – find “v” in string & extract to end – strstr ($string, “v”)
