Chapter 4 - String Manipulation and Regular Expressions

Question 1

Define and Show: isset()

Answer 1

Used to check that users have filled out all the required form fields.

if (!isset($name)) {
echo “You need to go back and write your name.”;
}

Question 2

Define and Show: mail()

Answer 2

Used to set up your PHP installation to point at your mail sending program.

mail($toaddress, $subject, $mailcontent, $fromaddress);

Question 3

Define and Show: ltrim()

Answer 3

Used to remove the whitespace on the left side of the string.

$name = ltrim($_POST[‘name’]);

Question 4

Define and Show: rtrim()

Answer 4

Used to remove the whitespace on the right side of the string.

$name = rtrim($_POST[‘name’]);

Question 5

Define and Show: trim()

Answer 5

Used to remove the whitespace from the start and end of the string.

$name = trim($_POST[‘name’]);

Question 6

Define and Show: nl2br()

Answer 6

Takes a string as a parameter and replaces all the newlines with an XHTML <br></br> tag.

echo nl2br($mailcontent);

Question 7

Define and Show: print()

Answer 7

Does the same this as echo, which is it prints the string to the screen, but with print() it returns true or false.

print(“Hello my name is Rob”);

Question 8

Define and Show: printf()

Answer 8

Prints a formatted string to the browser.

printf(“Hello my name is Rob”);

Question 9

Define and Show: sprintf()

Answer 9

Returns a formatted string.

sprintf(“Hello my name is Rob”);

Question 10

Define and Show: %s

Answer 10

Replace with string (the s means string).

Other parameters:
b: binary number
c: character
d: decimal number
f: floating-point number
o: octal number
s: string
u: unsigned decimal
x: hexadecimal number with lowercase letters for the digits a-f.
X: hexadecimal number with uppercase letters for the digits A-F. 

printf(“Total amount of order is %.2f”, $total);

Question 11

Define and Show: vprintf() & vsprintf()

Answer 11

These are a variant of printf() and sprintf(). They accept two parameters: the format string and an array of the arguments.

vprintf(“You win!”, $reward); // prints to the browser
vsprintf(“You win!”, $reward); // returns a formatted string

Question 12

Define and Show: strtoupper()

Answer 12

Turns string to uppercase.

$uppercaseName = strtoupper($_POST[‘name’]);

Question 13

Define and Show: strtolower()

Answer 13

Turns string to lowercase.

$lowercaseName = strtolower($_POST[‘name’]);

Question 14

Define and Show: ucfirst()

Answer 14

Capitalizes first character of string if it’s alphabetic.

$name = ucfirst($_POST[‘name’]);

Question 15

Define and Show: ucwords()

Answer 15

Capitalizes first character of each word in the string that begins with an alphabetic character.

$name = ucwords($_POST[‘name’]);

Question 16

Define and Show: addslashes()

Answer 16

Takes a string parameter and returns the reformatted string. In this case, the slashes would be added to the string.

$feedback = addslashes(trim($_POST[‘feedback’’]));

Question 17

Define and Show: stripslashes()

Answer 17

Takes a string parameter and returns the reformatted string. In this case, the slashes would be stripped from the string.

$feedback = stripslashes(trim($_POST[‘feedback’’]));

Question 18

Define and Show: explode()

Answer 18

Takes a string input and splits it into pieces on a specified separator string all at one time.

$email_array = explode(‘@’, $email);

You can now use it for something like:
if ($email_array[1] == “bigcustomer.com”) {
$toaddress = “bob@example.com”;
} else {
$toaddress = “feedback@example.com”;
}

Question 19

Define and Show: implode() or join()

Answer 19

They are the same. They join the bits of string together.

$new_email = implode(‘@’, $email_array);

Question 20

Define and Show: strtok();

Answer 20

Similar to explode(), but strtok() get pieces (tokens) from a string one at a time.

$feedback = “Thanks for everything.”;

$token = strtok($feedback, “ “);

// This only finds the first separator then stops
echo $token."<br />";

// This separates everything in the string
while ($token != "") {
     $token = strtok(" ");
     echo $token."<br />"; 
}

Question 21

Define and Show: substr();

Answer 21

Enables you to access a substring between a given start and end points of a string.

$test = ‘Your customer service is excellent’;
substr($test, 1);

Returns: our customer service is excellent
or
substr($test, 1, 13);
would return: our customer

Question 22

Define and Show: strlen()

Answer 22

Used to check the length of a string.

echo strlen(“hello”);

Question 23

Define and Show: strstr()

Answer 23

Used to find a string or character match within a longer string.

$feedback = “I really liked your shop.”;

if (strstr($feedback, ‘shop’))
$toaddress = ‘retail@example.com’;
}

Question 24

Define and Show: strchr()

Answer 24

Used to find a character match within a longer string. Finds the first occurrence and return the rest of the string.

$feedback = "I really liked your shop.";
echo strchr($feedback, 'sh');

Question 25

Define and Show: strrchr()

Answer 25

Used to find a character match within a longer string. Finds the LAST occurrence and return the rest of the string. This IS case sensitive;

$feedback = "I really liked your shop.";
echo strchr($feedback, 'r');

Question 26

Define and Show: stristr()

Answer 26

Used to find a character match within a longer string. Finds the LAST occurrence and return the rest of the string. This is NOT case sensitive;

$feedback = "I really liked your shop.";
echo strchr($feedback, 'r');

Question 27

Define and Show: strpos()

Answer 27

Same as starts() but strips() is recommended because it runs faster.

$test = "Hello world";
echo strpos($test, "o");

Question 28

Define and Show: str_replace()

Answer 28

Replaces all the instances of needle from haystack with new_needle and returns the new version of the haystack. The optional fourth parameter, count, contains the number of replacements made.

$roadRage = "You stupid mother fucker.";
$bad = "stupid mother fucker.";

$test = str_replace($bad, “sweet person you!”, $roadRage);
echo $test;

Question 29

Define and Show: substr_replace()

Answer 29

Finds and replaces a particular substring of a string based on its position.

$test = substr_replace($test, ‘X’, -1);

Question 30

Define and Show: ereg() and eregi()

Answer 30

It searches the search string, looking for matches to the regular expression in pattern.

eregi() is the exact same function but is NOT case sensitive.

if (eregi(“deliver | fulfill”, $feedback)) {
$toaddress = “shipping@example.com
}

Question 31

Define and Show: ereg_replace() and eregi_replace()

Answer 31

This function searches for the regular expression pattern in the search string and replace it with the string replacement.

eregi_replace() is the exact same function but is NOT case sensitive.

$pattern = 'delivery';
$replacement = 'shipping';
$body = eregi_replace($pattern, $replacement, $body);

Question 32

Define and Show: split()

Answer 32

This function splits the search string into substrings on the regular expression pattern and returns the substrings in an array.

$address = "username@example.com";
$arr = split("\.|@", $address);
while (list($key, $value) = each ($arr)) {
     echo "<br />".$value;
}

Question 33

Define: \ (backslash)

Answer 33

Escape Character.

Question 34

Define: ˆ (carrot) outside square brackets?

Answer 34

Match at start of string.

Question 35

Define: $ (dollar sign)

Answer 35

Match at end of string.

Question 36

Define: . (period)

Answer 36

Match any character except \n (new line).

Question 37

Define: | (pipe)

Answer 37

Start of alternative branch (read as OR).

Question 38

Define: ( (front parenthesis)

Answer 38

Start subpattern.

Question 39

Define: ) (end parenthesis)

Answer 39

End subpattern.

Question 40

Define: * (asterisk)

Answer 40

Repeat zero or more times.

Question 41

Define: + (plus sign)

Answer 41

Repeat one or more times.

Question 42

Define: { (front curly brace)

Answer 42

Start min/max quantifier.

Question 43

Define: } (end curly brace)

Answer 43

End min/max quantifier.

Question 44

Define: ? (question mark)

Answer 44

Mark a subpattern as optional.

Question 45

Define: ˆ (carrot) inside square brackets?

Answer 45

NOT, only if used in initial position.

Question 46

Define: - (dash)

Answer 46

Used to specify character strings.

Question 47

Define: [[:alnum:]]

Answer 47

Alphanumeric characters

Question 48

Define: [[:alpha:]]

Answer 48

Alphabetic characters

Question 49

Define: [[:lower:]]

Answer 49

Lowercase letters

Question 50

Define: [[:upper:]]

Answer 50

Uppercase letters

Question 51

Define: [[:digit:]]

Answer 51

Decimal digits

Question 52

Define: [[:xdigit:]]

Answer 52

Hexadecimal digits

Question 53

Define: [[:punct:]]

Answer 53

Punctuation

Question 54

Define: [[:blank:]]

Answer 54

Tabs and spaces

Question 55

Define: [[:space:]]

Answer 55

Whitespace characters

Question 56

Define: [[:cntrl:]]

Answer 56

Control characters

Question 57

Define: [[:print:]]

Answer 57

All printable characters

Question 58

Define: [[:graph:]]

Answer 58

All printable characters except for space