Zend Php 5.5 Certification Study Guide: Chapter 2 Functions, Chapter 3 Strings

Front 1

Why doesn't the concept of "void" apply in PHP functions?

Back 1

PHP functions always return a value, even if it's not specified.

Front 2

What does a function return if no return value is set?

Back 2

NULL

Front 3

How do you return by reference?

Back 3

function &functionName()'

Front 4

How do you return an expression by reference?

Back 4

You can't, only variables can be returned by reference.

Front 5

By default how will an object be returned?

Back 5

By reference

Front 6

What is a common reason to return by reference?

Back 6

For resources, like database connections.

Front 7

What happens if you don't return a variable in a function that returns by reference?

Back 7

You get an error.

Front 8

What are the three variable scopes?

Back 8

Global, Function and Class

Front 9

How can you access a variable with function scope once the function is no longer available?

Back 9

You can't

Front 10

How can you access global variables inside a function

Back 10

1. Importing with 'global $a;' or 2. use the superglobal array $GLOBALS['a'];

Front 11

What's an efficient way to access multiple global variables inside a function

Back 11

Importing with a comma separated list of variables.

Front 12

Why do developers prefer the superglobal array over importing?

Back 12

It adds confusion to the code and $GLOBALS contains everything you would need.

Front 13

What will happen if you pass more arguments to a function than were defined in the declaration?

Back 13

Nothing, PHP doesn't care.

Front 14

What will happen if you pass fewer arguments to a function than were defined in the declaration

Back 14

PHP throws an error.

Front 15

How can you give an argument a default value of an expression?

Back 15

You can't

Front 16

Where should argument's with default values be?

Back 16

The rightmost positions in the list

Front 17

What can you specify for type-hints?

Back 17

Any class or interface name, array, or callable

Front 18

How do you type-hint an argument?

Back 18

Prepend the argument with the type.

Front 19

Can you type-hint with a default value?

Back 19

Yes, but the default value must be null.

Front 20

What happens if you pass an invalid value into a type-hinted argument with a default value?

Back 20

PHP throws an error.

Front 21

How do you pass an argument by reference?

Back 21

function functionName(&$arg1);

Front 22

How do you pass an expression as a by-reference argument?

Back 22

You can't, only variables can be passed by reference.

Front 23

Can you set a default value for a by-reference argument?

Back 23

Yes, but only in PHP 5+

Front 24

What happens to a variable that is created by a default by-reference argument?

Back 24

It is destroyed upon return.

Front 25

What does func_get_args() do?

Back 25

Returns an array of arguments passed to your function

Front 26

What does func_num_args() do?

Back 26

Returns the number of arguments passed to your function

Front 27

What does func_get_arg() do?

Back 27

Returns the argument value when you input the argument's position.

Front 28

How do you declare a variadics?

Back 28

function functionName($arg1, ...$args)'

Front 29

Where can you declare a variadics?

Back 29

Only the leftmost argument.

Front 30

What is a variadics?

Back 30

Allow you to explicitly denote a function as accepting a variable length of arguments; no longer having to manually retrieve arguments and separate them from named arguments

Front 31

In function myFunction(...$args) how do I access each argument?

Back 31

foreach ($args as $arg)

Front 32

How do you pass variadics by reference?

Back 32

function myFunction(&...$args)

Front 33

How do you type-hint variadics?

Back 33

function myFunction(Type ...$args)

Front 34

What is 'unpacking'?

Back 34

Passing an array-like data structure into an argument list?

Front 35

How would you use unpacking in str_replace?

Back 35

$args = ["v1", "v2", "v3"]; str_replace(...$args);

Front 36

A string in single quotes represents what?

Back 36

Simple Strings, almost all characters are used literally.

Front 37

A string in double quotes represents what?

Back 37

Complex Strings, allow for special escape sequences and variable substitutions.

Front 38

What is the format of an escape sequence?

Back 38

A backslash followed by one or more characters.

Front 39

What syntax can you use to interpolate a variable in a string that cannot be readily parsed?

Back 39

Wrap the variable in braces. "Hello {$name[1]}"

Front 40

What is a heredoc?

Back 40

A syntax to declare complex strings that can easily incorporated double quotes.

Front 41

What is the heredoc syntax?

Back 41

<

Front 42

What is the difference between nowdoc and heredoc?

Back 42

Nowdoc does not interpolate or use escape sequences.

Front 43

What is the naming convention of heredoc identifiers?

Back 43

Upper Case

Front 44

What is the nowdoc syntax?

Back 44

<<<'KEYWORD'...(newline)KEYWORD;

Front 45

Can you use heredoc when defining a class property?

Back 45

Only after PHP 5.3 and as of 5.6 you still can't interpolate.

Front 46

Can you use nowdoc when defining a class property?

Back 46

Yes, after PHP 5.3

Front 47

How do you typically escape characters in a string?

Back 47

Prepend character with a backslash

Front 48

How can you escape a brace?

Back 48

You can't, If you need a literal '{$', escape the dollar sign instead.

Front 49

What data can PHP strings store?

Back 49

Any data.

Front 50

What data can PHP string functions work on?

Back 50

Single byte characters only?

Front 51

How can you work on multibyte strings?

Back 51

With iconv and mbstring extensions

Front 52

What is the default_charset?

Back 52

UTF-8 (PHP 5.6+)

Front 53

What does strlen() do?

Back 53

It counts the number of bytes in a string.

Front 54

What does binary-safe mean?

Back 54

All Characters in the string are counted, regardless of value.

Front 55

What does strtr() do?

Back 55

Translates certain characters of a string into other characters. (Transliteration)

Front 56

What is strtr() often used for?

Back 56

To transform certain accented characters that cannot appear in URLs or email addresses into equivalent unaccented versions.

Front 57

How can you use a string as an array?

Back 57

Just use it the same way you would use an array.

Front 58

What would echo "abcdef"[1] output?

Back 58

b (PHP5.5+)

Front 59

What is a zero-based index?

Back 59

Index that starts at 0

Front 60

When should you use the identity operator on strings?

Back 60

Whenever you are performing a comparison that could lead to type-juggling problems?

Front 61

What is the difference between strcmp() and strcasecmp()

Back 61

strcasecmp() is case-sensitive

Front 62

What does strcmp() do?

Back 62

Compares two strings and returns zero if they are equal.

Front 63

What does the optional 3rd parameter of strcasecmp() do?

Back 63

It allows you to test a given number of characters only.

Front 64

What does substr_compare() do?

Back 64

It allows you to perform a comparison between two portions of strings.

Front 65

What are the simplest and fastest string search functions?

Back 65

strstr() and strpos()

Front 66

What does strpos() do?

Back 66

Returns the first position of the "needle" in a "haystack" or false if not found.

Front 67

Why should you use identity, not equivalence operator with strpos()?

Back 67

If the needle is in position 0, the equivalence operator would interpret it as false.

Front 68

What does strpos() optional third parameter do?

Back 68

It indicates the starting position of the haystack.

Front 69

What does strstr() do?

Back 69

Returns the part of the haystack that begins with the needle.

Front 70

What is the fastest string function?

Back 70

strstr()

Front 71

Does strstr() have an optional third parameter?

Back 71

No

Front 72

What are the case-insensitive versions of strpos and strstr?

Back 72

stripos(), stristr()

Front 73

What is the reverse search version of strpos?

Back 73

strrpos()

Front 74

What does strspn() do?

Back 74

It matches against a whitelist of allowed characters and returns the length of the first segment that contains said characters.

Front 75

What does strcspn() do?

Back 75

It matches against a blacklist of disallowed characters and returns the length of the first segment of string that don't have said characters.

Front 76

What do $c and $d do in strspn($a, $b, $c, $d)?

Back 76

$c sets the starting point and $d sets the length of string to examine.

Front 77

What do $a, $b, $c and $d do in str_replace($a, $b, $c, $d)

Back 77

$a is the needle, $b is the replacement string, $c is the haystack, $d is an optional by-reference variable that is filled with the number of substitutions made.

Front 78

What is str_ireplace()?

Back 78

Case-insensitive version of str_replace()

Front 79

How would you search and replace more than one needle at a time?

Back 79

Use arrays for needle and replacement string.

Front 80

What do $a, $b, $c and $d do in substr_replace($a, $b, $c, $d)

Back 80

$a is the input string, $b is the replacement string, $c indicates the starting point, $d is the optional end point.

Front 81

What do $a, $b, and $c do in substr($a, $b, $c)?

Back 81

$a is the input string, $b is the starting index, $c is the optional length of the substring.

Front 82

How can you start counting from the end of a string in substr()?

Back 82

Set the starting index to a negative number

Front 83

What does setlocale() do?

Back 83

It sets the location based on the locale and category you input. It affects formatting functions.

Front 84

What does number_format do?

Back 84

It separates digits into thousands, it is not locale-aware.

Front 85

What do $a, $b, $c and $d do in number_format($a, $b, $c, $d)?

Back 85

$a is the number, $b is number of decimals to round to (0 by default), $c will be the optional decimal separator, $d will be the optional thousands separator. $c and $d must be used together.

Front 86

What currency will money_format() use?

Back 86

It depends on your locale.

Front 87

What do $a and $b do in money_format($a, $b)?

Back 87

$a is a string, starting with '%', that crafts the format. $b is the number to be formatted.

Front 88

Why should you reset your locale after using setlocale()?

Back 88

It affects the whole script and different locales can have different rounding rules.

Front 89

What do the printf() family of functions do?

Back 89

They take an input string that specifies the output format and one or more values to return.

Front 90

What character is the formatting specifier?

Back 90

%

Front 91

How can you escape the formatting specifier?

Back 91

%%

Front 92

Describe a sign specifier

Back 92

A plus or minus symbol that determines how signed numbers are rendered.

Front 93

Describe a padding specifier

Back 93

Indicates what character should be used to make up the required output length if the input is not long enough

Front 94

Describe an alignment specifier

Back 94

Indicates if the output should be right or left aligned

Front 95

Describe a numeric width specifier

Back 95

Indicates the minimum length of the output

Front 96

Describe a precision specifier

Back 96

Indicates how many decimal digits should be displayed for floating points.

Front 97

Describe type specifier '%b'

Back 97

Output an integer as a binary number.

Front 98

Describe type specifier '%c'

Back 98

Output the character which has the input integer as its ASCII value.

Front 99

Describe type specifier '%d'

Back 99

Output a signed decimal number

Front 100

Describe type specifier '%e'

Back 100

Output a number using scientific notation (e.g., 3.8e+9)

Front 101

Describe type specifier '%u'

Back 101

Output an unsigned decimal number

Front 102

Describe type specifier '%f'

Back 102

Output a locale aware float number

Front 103

Describe type specifier '%F'

Back 103

Output a non-locale aware float number

Front 104

Describe type specifier '%o'

Back 104

Output a number using its Octal representation

Front 105

Describe type specifier '%s'

Back 105

Output a string

Front 106

Describe type specifier '%x'

Back 106

Output a number as hexadecimal with lowercase letters

Front 107

Describe type specifier '%X'

Back 107

Output a number as hexadecimal with uppercase letters

Front 108

What does sscanf() do?

Back 108

Accepts and parses formatted input.

Front 109

What do $a and $b do in sscanf($a, $b)

Back 109

$a is the input string, $b is the formatting pattern.

Front 110

What should be true when you use sscanf()

Back 110

The input data should follow a well-defined format, otherwise you can lose data.

Front 111

What does PCRE mean?

Back 111

Perl Compatible Regular Expressions.

Front 112

What's one drawback of using regex search and replace?

Back 112

It's much more computationally intensive than simple search and replace.

Front 113

What is the conventional PHP Regex delimiter?

Back 113

A Forward Slash

Front 114

What does the metacharacter . do?

Back 114

Match any character

Front 115

What does the metacharacter ^ do?

Back 115

Match the start of the string

Front 116

What does the metacharacter $ do?

Back 116

Match the end of the string

Front 117

What does the metacharacter \s do?

Back 117

Match any whitespace character

Front 118

What does the metacharacter \d do?

Back 118

Match any digit

Front 119

What does the metacharacter \w do?

Back 119

Match any “word” character

Front 120

What does the quantifier * do?

Back 120

The character can appear zero or more times

Front 121

What does the quantifier + do?

Back 121

The character can appear one or more times

Front 122

What does the quantifier ? do?

Back 122

The character can appear zero or one times

Front 123

What does the quantifier {n,m} do?

Back 123

The character can appear at least n times, and no more than m. Either parameter can be omitted to indicate a minimum limit with no maximum, or a maximum limit without a minimum, but not both.

Front 124

How can you make a quantifier greedy?

Back 124

They are greedy by default.

Front 125

How can you make a quantifier un-greedy?

Back 125

Append '?' to the quantifier.

Front 126

How can you change the behavior of a Regex?

Back 126

Add a pattern modifier after the closing delimiter.

Front 127

What does the pattern modifier i do?

Back 127

Makes pattern case-insensitive

Front 128

What does the pattern modifier m do?

Back 128

Indicates a multiline string. ^ and $ will match beginning and end of each line respectively.

Front 129

What does the pattern modifier s do?

Back 129

The 'any' character will also match newlines.

Front 130

What does the pattern modifier x do?

Back 130

Will ignore whitespace, newlines, characters after # and before newline.

Front 131

What does the pattern modifier e do?

Back 131

The 'eval' modifier lets you replace Regex with PHP expression. (Deprecated PHP 5.5)

Front 132

What does the pattern modifier U do?

Back 132

Makes quantifiers un-greedy by default.

Front 133

What does the pattern modifier u do?

Back 133

Treats pattern and subject as UTF-8. So it matches Characters instead of bytes.

Front 134

What is a sub-expression?

Back 134

Regex inside Regex. Defined by parenthesis.

Front 135

What does preg_match($a, $b, $c) do?

Back 135

Uses Regex $a to match agains $b. Return 1 if successful and if $c is included, returns all captured subpatterns.

Front 136

How do you ad parentheticals to a subpattern?

Back 136

(pattern)

Front 137

What does preg_match_all() do?

Back 137

Allows you to perform multiple matches on a string with a single Regex.

Front 138

What does PREG_PATTERN_ORDER do in preg_match_all's third parameter?

Back 138

Default behavior, each match is an array whose first array index is the entire matched string and each subsequent index is a capture group.

Front 139

What does PREG_SET_ORDER do in preg_match_all's third parameter?

Back 139

All matches for first capture group goes in first key, second goes in second key, etc. Good for named capture groups.

Front 140

What does PREG_OFFSET_CAPTURE do in preg_match_all's third parameter?

Back 140

Each matching string in the result is an array with the string itself and its offset from the beginning of the string.

Front 141

What does preg_replace($a, $b, $c) do?

Back 141

$a is the Regex pattern to match, $b is the replacement value (Can use captured subpatterns), $c is the string to search and replace.

Front 142

What's the benefit of $c being an array in preg_replace($a, $b, $c)?

Back 142

If you have multiple subjects to search and replace, it speeds things up as the regex only needs to be compiled once.