Conditionals Statements

1
Conditionals Statements

• if, else, elseif, and switch

2
if
lt? x 12 y 10 if(x gt y)
echo x is bigger than y ?gt

• The if statement is the most basic conditional
  statement in PHP and other programming languages.
• if(condition)
• statement

3
else
lt? if(x gt y) echo x is bigger than
y else echo x is NOT bigger than y
y x ?gt

• else allows you to specify what happens if the
  first condition is not met.
• if(condition)
• statement
• else
• alternate statement

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elseif
lt? if(x gt y) echo x is bigger than
y elseif(x lt y) echo x is smaller
than y else echo x is equal to y
?gt

• Use elseif to put multiple conditional
  statements into the same block of code.
• if(condition)
• statement
• elseif(alternate condition)
• alternate statement
• else
• alternate statement

5
switch
lt? switch(dayofweek) case "Saturday"
echo "Time for a BBQ" break case "Sunday"
echo "Spend some time in the hammock"
break default echo "Better get to
work!" ?gt

• If you have many elseif statements in a code
  block, it is probably better to use a switch
  statement.
• switch(expression)
• case value
• statement
• break
• case value
• statement
• break
• default
• statement

6
Exercise

• Create an HTML form with one text box. Instruct
  the user to type a number between 10 and 20
  (inclusive) in the text box.
• Create a PHP script that catches the users entry
  and displays a message explaining whether the
  answer is correct or incorrect.
• Add one more feature you think this script needs
  (for example, check to see if a non-numeric value
  was entered).
• Extra credit Create a second version of your
  script that uses a switch statement.