php_mysql_apache [Electronic resources]

Julie C. Meloni

نسخه متنی -صفحه : 323/ 60
نمايش فراداده

Workshop

The workshop is designed to help you anticipate possible questions, review what you've learned, and begin putting your knowledge into practice.

Quiz

1:

Which of the following variable names is not valid?

$a_value_submitted_by_a_user
$666666xyz
$xyz666666
$_____counter_____
$the first
$file-name
2:

What will the following code fragment output?

$num = 33;
(boolean) $num;
echo $num;
3:

What will the following statement output?

echo gettype("4");
4:

What will be the output from the following code fragment?

$test_val = 5.5466;
settype($test_val, "integer");
echo $test_val;
5:

Which of the following statements does not contain an expression?

4;
gettype(44);
5/12;
6:

Which of the statements in question 5 contains an operator?

7:

What value will the following expression return?

5 < 2

What data type will the returned value be?

Answers

A1:

The variable name $666666xyz is not valid because it does not begin with a letter or an underscore character. The variable name $the first is not valid because it contains a space. $file-name is also invalid because it ontains a non-alphanumeric character.

A2:

The fragment will print the integer 33. The cast to Boolean produces a converted copy of the value stored in $num. It does not alter the value actually stored there.

A3:

The statement will output the string "string".

A4:

The code will output the value 5. When a double is converted to an integer, any information beyond the decimal point is lost.

A5:

They are all expressions because they all resolve to values.

A6:

The statement 5/12; contains a division operator.

A7:

The expression will resolve to false, which is a Boolean value.

Activities

1:

Create a script that contains at least five different variables. Populate them with values of different data types and use the gettype() function to print each type to the browser.

2:

Assign values to two variables. Use comparison operators to test whether the first value is

  • The same as the second

  • Less than the second

  • Greater than the second

  • Less than or equal to the second

Print the result of each test to the browser.

Change the values assigned to your test variables and run the script again.