DIG 4530c Lecture 2:

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Media E-Commerce I
DIG 4530c - Lecture 2 Rapid Introduction To
PHP Programming Michael Moshell University of
Central Florida
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• The Objectives
• Acquire/refresh key programming ideas
• Learn how to debug a small program

3

• The Strategy
• Start slow, make sure you got it

850
4

• The Strategy
• Start slow, make sure you got it
• Accelerate rapidly
• Lose 25 of you

850
900
5

• The Strategy
• Start slow, make sure you got it
• Accelerate rapidly
• Lose 25 of you
• See (some of)
• you in office

850
900
930
6

• The Strategy
• Start slow, make sure you got it
• Accelerate rapidly
• Lose 25 of you
• See (some of)
• you in office

Drop/ add
850
900
930
Wed
7

• The Strategy
• Start slow, make sure you got it
• Accelerate rapidly
• Lose 25 of you
• See (some of)
• you in office
• Greet late arrivers

Drop/ add
?
850
900
930
Wed
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Task List 1 Random victims
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Concept (-1) "Hello World"
The first program you write in a new
language lt?php print "Hello world!" ?gt The
"Daisy" song ... HAL in 2001
www.hexus.net
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Concept 0 PHP in HTML
PHP is an embedded language. It can exist INSIDE
an HTML document. lthtmlgt ltbodygt lt?php x43
?gt lth2gt Welcome to the lt?php print x
?gtrd Reunion!lt/h2gt lt/bodygt lt/htmlgt
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Concept 1 Data types
Numbers - Integers 0, 2, 4, 8 - Floating point
2.45, -888.99 no real distinction in PHP
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Concept 1 Data types
Numbers - Integers 0, 2, 4, 8 - Floating point
2.45, -888.99 no real distinction in
PHP Strings (of characters) -Joe Wilson -My
left foot -3, 47, 238, 222.44
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Concept 1 Data types
Numbers - Integers 0, 2, 4, 8 - Floating point
2.45, -888.99 no real distinction in
PHP Strings (of characters) -Joe Wilson -My
left foot -3, 47, 238, 222.44 Boolean true,
false
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Concept 1 Data types
PHP plays fast and loose with types. You can
mix and match them, and it Does the best it can
to figure out your Meaning. Examples coming
soon.
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Concept 2 Variables (simple)
Think of a variable as a labelled box. x
Name of the Variable (always begins With )
Contents Can be number, String or Boolean.
The CONTENTS of all the variables in a
program Represent its STATE or MEMORY.
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Concept 3 Assignments,Constants
Putting something into a variable x
Before the assignment
x 47
The computer executes this statement, or command.
x
47
After the assignment
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Concept 3 Assignments,Constants
Putting something into a variable x
Before the assignment
x 47
The computer executes this statement, or command.
x
47
After the assignment
Thats a constant (something that doesnt change.)
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Concept 3 Assignment
Putting something ELSE into a variable x
47
Before the assignment
x 321
The computer executes this statement, or command.
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Concept 3 Assignment
Putting something ELSE into a variable x
47
Before the assignment
x 321
The computer executes this statement, or command.
x
321
After the assignment
The previous contents are entirely replaced.
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Concept 4 Expressions
In an Assignment The Expression on the RIGHT is
computed and then it is put into the variable.
x 33 22
First compute 3322, yields 55 Then dump it into
x.
x
55
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About Variable Names
Safest names are plus text-strings, like
price You can do a lot of other stuff in php,
like _this But dont do this it has VERY
confusing consequences.
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Concept 4 Expressions
The is an EVIL TRICKY SYMBOL. It really
should be an arrow like ? Because it does NOT
mean equals! It means evaluate right, copy to
left. pronounce "is replaced by the value of..."
x 33 x
Before execution
After execution
x
x
55
?
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Concept 4 Expressions
The is an EVIL TRICKY SYMBOL. It really
should be an arrow like ? Because it does NOT
mean equals! It means evaluate right, copy to
left.
x 33 x
Before execution
After execution
x
x
55
88
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Concept 5 Hand Simulation
Acting out what the program will do. Your job
Answer question at bottom.
x 3 y 2x 7 z 4 x y
z Print x
x
3
y
z
What is printed?
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Concept 5 Hand Simulation
Acting out what the program will do. Your job
Answer question at bottom.
x 3 y 2x 7 z 4 x y
z Print x
x
3
y
13
z
What is printed?
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Concept 5 Hand Simulation
Acting out what the program will do. Your job
Answer question at bottom.
x 3 y 2x 7 z 4 x y
z Print x
x
3
y
13
z
4
What is printed?
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Concept 5 Hand Simulation
Acting out what the program will do. Your job
Answer question at bottom.
x 3 y 2x 7 z 4 x y
z Print x
x
3
17
y
13
z
4
What is printed?
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Concept 5 Hand Simulation
Acting out what the program will do. Your job
Answer question at bottom.
x 3 y 2x 7 z 4 x y
z Print x
x
3
17
y
13
z
4
What is printed? 17 is printed.
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Practice Hand Simulation
Acting out what the program will do. Your job
Answer question at bottom.
x 2 y 3x -4 z 3-y y y
z Print y
x
y
z
What is printed?
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Practice Hand Simulation
Acting out what the program will do. Your job
Answer question at bottom.
x 2 y 3x -4 z 3-y y y
z Print y
x
y
z
What is printed? 3 is printed.
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Practice Hand Simulation
Acting out what the program will do. Your job
Answer question at bottom.
x 2 y 3x -4 z 3-y y y
z Print y
2
x
y
z
What is printed? 3 is printed.
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Practice Hand Simulation
Acting out what the program will do. Your job
Answer question at bottom.
x 2 y 3x -4 z 3-y y y
z Print y
2
x
2
y
z
What is printed? 3 is printed.
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Practice Hand Simulation
Acting out what the program will do. Your job
Answer question at bottom.
x 2 y 3x -4 z 3-y y y
z Print y
2
x
2
y
1
z
What is printed? 3 is printed.
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Practice Hand Simulation
Acting out what the program will do. Your job
Answer question at bottom.
x 2 y 3x -4 z 3-y y y
z Print y
2
x
2
y
3
1
z
What is printed? 3 is printed.
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Concept 6 Comments
Human-readable reminders in the code. Three ways
to make them this hides the rest of the
line // and so does this
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Concept 6 Comments
Human-readable reminders in the code. Three ways
to make them this hides the rest of the
line // and so does this / this hides
everything until you do its opposite like this
/
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Concept 7 Logical expressions and code blocks
cost43 limit100 // and then later in the
program if (keyltlimit) print This is a
legal expenditure! else print No!
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Concept 7 Logical expressions and code blocks
cost43 limit100 // and then later in the
program if (keyltlimit) print This is a
legal expenditure! else print No!
Logical Expression (T/F)
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Concept 7 Logical expressions and code blocks
cost43 limit100 // and then later in the
program if (keyltlimit) print This is a
legal expenditure! else print No!
Logical Expression (T/F)
Code block
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Aside PHP cares about Case!
Cost Is not the same as cost
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Concept 8 Loops
Computers are useless for doing things
ONCE. k1 While (klt100) print
k k2k What will this print?
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Aside What will it LOOK like?
Remember the output goes to a browser. k1 Whil
e (klt100) print k k2k What will
this print? 248163264
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Aside What will it LOOK like?
Remember the output goes to a browser. k1 Whil
e (klt100) print k.\n k2k What
will this print?
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Aside What will it LOOK like?
Remember the output goes to a browser. k1 Whil
e (klt100) print k.\n k2k What
will this print? 2 4 8 16 32 64 BUT lets VIEW
SOURCE.
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Aside What will it LOOK like?
To make it react as if to HTML k1 While
(klt100) print k.ltbr /gt k2k What
will this print?
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Aside What will it LOOK like?
To make it react as if to HTML k1 While
(klt100) print k.ltbr /gt k2k What
will this print?
2 4 8 16 32 64
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Aside What will it LOOK like?
To make it react as if to HTML k1 While
(klt100) print k.ltbr /gt k2k We
concatenate a NUMBER k and a STRING ltbr /gt ..
It becomes a string.
We dissect This thing. DOT (.) means string
Concatenation (stick em together)
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PHP Errors
Lets sabotage the program. Omit the
semicolon n1 While (nlt100) print
n.\n n2n .. And see what
happens. Parse error syntax error, unexpected
T_VARIABLE in C\wamp\www\little.php on line 6
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What will it LOOK like?
Lets try to make a nice table appear. Print
lttable border1gt n1 While (nlt100) print
lttrgtlttdgt.n.lt/tdgtlt/trgt n2n Print
lt/tablegt
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A microsoft GOTCHA!
So-called Smart Quotes dont work in PHP. You
need DUMB QUOTES like " Print " lttable border1gt
" n1 While (nlt100) print " lttrgtlttdgt ".n.
" lt/tdgtlt/trgt " n2n Print " lt/tablegt "
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PHP emitting HTML
Now we will use our loop to make a
table. n1 While (nlt100) print
n.\n n2n .. And see what
happens. Parse error syntax error, unexpected
T_VARIABLE in C\wamp\www\little.php on line 6
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Practice emitting HTML

• Make this table appear!
• 2. Make this table appear.
• 3. How about this one? ( appears whenever the
• contents exceed 16. Use an IF inside a loop)
• 4. For the advanced among you

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For Wed or Fri Lab

• If you have a laptop
• get WAMP or MAMP
• Install it
• Optional Get a text/reference book on PHP/mySQL
• Everybody write up Task List 1
• Write the answers. Well use them
• in next weeks lecture.

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And now the Diagnostic Quiz
You are free to use any knowledge you gained
today ... But I realize that it may not have
baked into your brains yet ...
simpsonstrivia.com