php_mysql_apache [Electronic resources] نسخه متنی

Which of the following variable names is not valid?

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

What will the following code fragment output?

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

What will the following statement output?

echo gettype("4");

What will be the output from the following code fragment?

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

Which of the following statements does not contain an expression?

4;
gettype(44);
5/12;

Which of the statements in question 5 contains an operator?

What value will the following expression return?

5 < 2

What data type will the returned value be?

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.

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.

The statement will output the string "string".

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

They are all expressions because they all resolve to values.

The statement 5/12; contains a division operator.

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

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.

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.