Anna Filina's Slides from her April 26, 2012 presentation to Montreal Girl Geeks

1. FooLab
PHP Workshop #1
First Programming Experience

2. 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.
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3. 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.
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4. Programming FooLab
Describing procedures
Input
Find Password
username
username matches?
and password
Yes No
Open Display error
account page message
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5. Functions FooLab
One step in the whole program
pi 3.141592 ...
26, 58 max 58
Y-m-d date 2012-04-26
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6. 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.
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7. Functions FooLab
php> echo pi();
php> echo max(26,58);
php> echo max (26, 58);
php> echo date("Y-m-d");
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8. Interpreter FooLab
• I like like
php> echo echo;
• I like the word “like”
php> echo "echo";
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9. 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.
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10. Variables FooLab
• "Programming is cool"
• "Design is cool"
• "Video editing is cool"
php> $hobby = "Design";
php> echo $hobby;
php> echo "$hobby is cool";
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11. FooLab
Design
• Use the $ sign to refer
to the bin’s name.
hobby
• Use the = sign to put
content in the bin.
$hobby = "Design"
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12. FooLab
Design
• No sign is needed to get
the bin’s content out.
hobby
• A variable is where we
put a value.
echo $hobby
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13. 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
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14. 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.
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15. 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.
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16. Movie Price FooLab
• Movie costs 12$
• Popcorn costs 8$
• Popcorn can be shared between two people.
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17. FooLab
• What happens with popcorn when we have an odd
number of people?
ceil(3 / 2);
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18. 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
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19. 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
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20. Answer FooLab
<?php
$people = 3;
echo ceil($people / 2) * 8 + $people * 12;
?>
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21. FooLab
Functions
Understanding Them and Writing Your Own

22. FooLab
26, 58 max 58
• Accept parameters
• Perform steps
• Return result
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23. 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);
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24. What Happened? FooLab
Number of Price was
Price came out
people went in displayed
(5) 84 echo
movie_price
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25. FooLab
Working With Text and
Numbers
Using String and Math Functions

26. 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);
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27. Position zero FooLab
• Many programming languages start counting at zero.
F o o L a b
advance by: 0 1 2 3 4 5
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28. 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: $letters = “abcdefg...”
• substr(text, start, length)
• rand(min, max)
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29. Answer FooLab
function area($h, $w) {
return $h * $w;
}
function rand_letter() {
$letters = "abcdefghijklmnopqrstuvwxyz";
return substr($letters, rand(0,25), 1);
}
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30. FooLab
Conditions
If It’s Cold, Wear a Coat

31. FooLab
• Expression: produces a value of true or false.
• Execute a process only if the expression is true.
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32. Writing Conditional
Statements FooLab
• Open the script.php file in your text editor.
$temp = 12;
if ($temp < 15) {
echo "Wear a coat";
}
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33. FooLab
$temp = 20;
if ($temp < 15) {
echo "Wear a coat";
}
else {
echo "It's hot enough";
}
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34. Mental Exercise FooLab
1 < 1
1 == 1
1 != 1
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35. Combining Expressions FooLab
• Temperature is less than 5 degrees
and
wind is greater than 30 km/h
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36. Logical Operators FooLab
true && true
true && false
true || false
false || false
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37. FooLab
Repetition
Lather. Rinse. Repeat.

38. Vocabulary FooLab
• Repetition (to repeat)
• Loop (to loop)
• Iteration (to iterate)
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39. 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
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40. 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 $i = 4
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41. Chorus FooLab
for ($i = 1; $i <= 4; $i++) {
echo "This song is just six words longn";
}
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42. Array FooLab
An ordered set of related elements
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43. Array FooLab
An ordered set of related elements
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44. 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.
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45. Acces Elements By Index FooLab
$movies = array("Titanic", "Shrek", "Die Hard");
echo $movies[1];
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46. Iterating Over Arrays FooLab
$movies = array("Titanic", "Shrek", "Die Hard");
foreach ($movies as $movie) {
echo "I watched $movien";
}
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47. Getting Index and Value FooLab
• In addition to the value, you can also get the index for
each iteration:
foreach ($movies as $index => $movie)
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48. 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;
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49. 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”
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50. 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;
}
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51. 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!
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52. 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/
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53. Resources FooLab
• php.net has a manual and a reference for all functions.
• phpquebec.org is the PHP users group in Montreal.
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