Intro to PHP for Beginners

FooLab

PHP Workshop #1
First Programming Experience

Who are you? FooLab

• Have you ever written PHP before?

• Have you ever written computer code before?

• Have you ever seen computer code?

• Ask for the name of your neighbor on each side.

2

Anna Filina FooLab

• PHP Quebec - user group, organizer.

• ConFoo - non for proﬁt Web conference, organizer.

• FooLab Inc. - IT consulting, vice-president.

• I write code.

• I train people.

3

Programming FooLab
Describing procedures

Input
Find Password
username
username matches?
and password
Yes No

Open Display error
account page message

4

Functions FooLab

One step in the whole program

pi 3.141592 ...

26, 58 max 58

Y-m-d date 2012-04-26

5

Interactive Shell FooLab

• We can see result of PHP code as we type it.

• Open your console. Type phpsh

• After each line of code, press enter to execute it.

6

Functions FooLab

php> echo pi();

php> echo max(26,58);

php> echo max (26, 58);

php> echo date("Y-m-d");

7

Interpreter FooLab

• I like like

php> echo echo;

• I like the word “like”

php> echo "echo";

8

Data Types FooLab

• Integer, can’t confuse with commands or functions:

php> echo 33;

• String, use quotes:

php> echo "Programming is cool";

• There are more types, but that’s for later.

9

Variables FooLab

• "Programming is cool"
• "Design is cool"
• "Video editing is cool"

php> $hobby = "Design";
php> echo $hobby;
php> echo "$hobby is cool";

10

FooLab

Design
• Use the $ sign to refer
to the bin’s name.
hobby
• Use the = sign to put
content in the bin.
$hobby = "Design"

11

FooLab

Design
• No sign is needed to get
the bin’s content out.
hobby
• A variable is where we
put a value.
echo $hobby

12

Writing Code in Files FooLab

• It’s easier to write multiple lines of code in a ﬁle.

• Open your text editor.

• Open the ﬁle /var/www/php1/script.php

13

FooLab
• Quit the interactive shell by typing:

php> q

• Now you can run your ﬁle using:

$ php /var/www/php1/script.php

• Repeat the previous command by pressing the up arrow.

• Every time we edit our ﬁle, we’ll test the code.
14

FooLab

• The ﬁle currently contains the following text:

<?php
$hobby = "Design";
echo "$hobby is cool";
?>

• The ﬁle ends in empty lines. Don’t delete them.

15

Movie Price FooLab

• Movie costs 12$

• Popcorn costs 8$

• Popcorn can be shared between two people.

16

FooLab

• What happens with popcorn when we have an odd
number of people?

ceil(3 / 2);

17

Procedure FooLab

Calculate total movie cost based on number of people

Set number of Get number of
people popcorns Popcorns * 8
(variable) required

Display sum Tickets * 12

18

Practice! FooLab
• Write a script that, given any number of people,
calculates the total price for movie and popcorn.

• Set number of people (variable)

• Get number of popcorns required

• Popcorns * 8

• Tickets * 12

• Display sum
19

Answer FooLab

<?php
$people = 3;
echo ceil($people / 2) * 8 + $people * 12;
?>

20

FooLab

Functions
Understanding Them and Writing Your Own

FooLab

26, 58 max 58

• Accept parameters

• Perform steps

• Return result

22

Create and Call a Function FooLab

• Wrap code in a function:
function movie_price($people) {
$total = ceil($people / 2) * 8 + $people * 12;
return $total;
}

• Call function:

echo movie_price(5);

23

What Happened? FooLab

Number of Price was
Price came out
people went in displayed

(5) 84 echo

movie_price

24

FooLab

Working With Text and
Numbers
Using String and Math Functions

String and Math Functions FooLab

• Open the interactive shell: phpsh

php> echo rand(1, 3);
php> echo rand(1, 100);
php> echo strlen("FooLab");
php> echo substr("FooLab", 3);
php> echo substr("FooLab", 3, 1);

26

Position zero FooLab

• Many programming languages start counting at zero.

F o o L a b
advance by: 0 1 2 3 4 5

27

Practice! FooLab

• Write a function that calculates a rectangle’s area using
height and width.

• Write a function that returns a random letter from the
alphabet. Hint: $letters = “abcdefg...”

• substr(text, start, length)

• rand(min, max)

28

Answer FooLab

function area($h, $w) {
return $h * $w;
}

function rand_letter() {
$letters = "abcdefghijklmnopqrstuvwxyz";
return substr($letters, rand(0,25), 1);
}

29

FooLab

Conditions
If It’s Cold, Wear a Coat

FooLab

• Expression: produces a value of true or false.

• Execute a process only if the expression is true.

31

Writing Conditional
Statements FooLab

• Open the script.php ﬁle in your text editor.

$temp = 12;
if ($temp < 15) {
echo "Wear a coat";
}

32

FooLab

$temp = 20;
if ($temp < 15) {
echo "Wear a coat";
}
else {
echo "It's hot enough";
}

33

Mental Exercise FooLab

1 < 1

1 == 1

1 != 1

34

Combining Expressions FooLab

• Temperature is less than 5 degrees
and
wind is greater than 30 km/h

35

Logical Operators FooLab

true && true

true && false

true || false

false || false

36

FooLab

Repetition
Lather. Rinse. Repeat.

Vocabulary FooLab

• Repetition (to repeat)

• Loop (to loop)

• Iteration (to iterate)

38

Writing Loops FooLab

• for (initially ; iterate this time? ; after each iteration)

for ($i = 1; $i <= 3; $i++) {
echo $i;
}

• $i++ is the same as $i = $i + 1

39

What Happened? FooLab
$i = 1; $i <= 3; $i++

$i <= 3 $i <= 3 $i <= 3 $i <= 3

echo $i echo $i echo $i stop

$i = 2 $i = 3 $i = 4

40

Chorus FooLab

for ($i = 1; $i <= 4; $i++) {
echo "This song is just six words longn";
}

41

Array FooLab
An ordered set of related elements

42

Array FooLab
An ordered set of related elements

43

What Is An Array? FooLab

page page page
book
0 1 2

number number "Text"

• You can put books in boxes for “nested” arrays,
but that’s for another day.
44

Acces Elements By Index FooLab

$movies = array("Titanic", "Shrek", "Die Hard");
echo $movies[1];

45

Iterating Over Arrays FooLab

$movies = array("Titanic", "Shrek", "Die Hard");

foreach ($movies as $movie) {
echo "I watched $movien";
}

46

Getting Index and Value FooLab

• In addition to the value, you can also get the index for
each iteration:

foreach ($movies as $index => $movie)

47

Concatenation FooLab
• Link bits of text together using a dot (.)

echo "You rolled " . rand(2, 12);

• Useful in a loop

$sequence = "";
for ($i = 1; $i <= 10; $i++) {
$sequence = $sequence . rand(0, 9);
}
echo $sequence;
48

Practice! FooLab

• Write a function that creates a random 9-character,
pronouncable password.

• 3 cyllables, 3 letters each
• Consonant, vowel, consonant
• Should produce something like this:
“hagrokwag”

49

Answer FooLab
function rand_vowel() {
$vowels = "aeiou";
return substr($vowels, rand(0,4), 1);
}
function rand_consonant() {
$consonants = "bcdfghjklmnpqrstvwxyz";
return substr($consonants, rand(0,20), 1);
}
function rand_password() {
$pass = "";
for ($i = 1; $i <= 3; $i++ ) {
$pass = $pass.rand_consonant().rand_vowel().rand_consonant();
}
return $pass;
}

50

Trivia FooLab

• 6 ^ 21 + 3 ^ 5
gives over 20 quadrillions combinations

• It will take millions of years for a computer
to try them all

• And you can pronounce it, making it easy to memorize!

51

Next Steps FooLab
• Go to phpjunkyard.com

• Download some script

• See how it works

• Play with the code

• Anything you put in /var/www/php1 can be accessed in
the browser: http://php1.local/
52

Resources FooLab

• php.net has a manual and a reference for all functions.

• phpquebec.org is the PHP users group in Montreal.

53

Intro to PHP for Beginners

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