ch3 questions

Question 1

What tag is used to cause PHP to start interpreting program code? And what is the short form of the tag?

Answer 1

<?

the short form is deprecated

Question 2

What are the two types of comment tags?

Answer 2

// single line comment
/* multiline
 comment */

Question 3

Which character must be placed at the end of every PHP statement?

Answer 3

;

Question 4

Which symbol is used to preface all PHP variables?

Answer 4

$

Question 5

What can a variable store?

Answer 5

numbers, strings, arrays

Question 6

What is the difference between $variable = 1 and $variable == 1?

Answer 6

$variable = 1 declares $variable as 1

$variable == 1 compares $variable to 1

Question 7

Why do you suppose an underscore is allowed in variable names (e.g., $current_user) whereas hyphens are not (e.g., $current-user)?

Answer 7

Because the hyphen ( - ) is also a subtraction operator

Question 8

Are variable names case-sensitive?

Answer 8

Yes

Question 9

Can you use spaces in variable names?

Answer 9

No

Question 10

How do you convert one variable type to another (say, a string to a number)?

Answer 10

To convert a variable type to another, reference it and PHP will automatically convert it for you.

Question 11

What is the difference between ++$j and $j++?

Answer 11

++$j increment before

$j++ increment after

Question 12

Are the operators && and ‘and’ interchangeable?

Answer 12

Yes but && has higher precedence than and

Question 13

How can you create a multiline echo or assignment?

Answer 13

Using heredoc tags or quotation marks
<<<_TAGNAME
multiline
echo
_TAGNAME;
(the closing tag should be at the beginning of a line and followed by a semicolon, nothing else can be on the line)

Question 14

Can you redefine a constant?

Answer 14

No

Question 15

How do you escape a quotation mark?

Answer 15

By prefacing it with \

Question 16

What is the difference between echo and print commands?

Answer 16

The echo and print commands are similar in that they are both constructs, except that print behaves like a PHP function and takes a single argument, while echo can take multiple arguments.

Question 17

What is the purpose of functions?

Answer 17

Functions are used to separate out sections of code that perform a particular task and make it easier to execute that task repeatedly.

Question 18

How can you make a variable accessible to all parts of a PHP program?

Answer 18

By making the variable a global variable. Using the syntax:

global $variable;

Question 19

If you generate data within a function, what are a couple of ways to convey the data to the rest of the program?

Answer 19

If you generate data within a function, you can convey the data to the rest of the program by returning a value or modifying a global variable.

Question 20

What is the result of combining a string with a number?

Answer 20

The number becomes part of the string