PHP Strings
This quiz is meant for self-study to aid in learning/memorizing the string functions in PHP.
Questions and Answers
- 1.
What is the output of the following code snippet? $str = 'asdfghyo off on off'; $replace_pairs = array('a' => 'q', 's' => 'w', 'd' => 'e', 'f' => 'r', 'y' => 'z', 'o' => 'i', 'off' => 'on', 'on' => 'off'); echo strtr($str, $replace_pairs);
- A.
Qwerghzi on off on
- B.
Qwerghzo on off on
- C.
Qwerghzi on on on
- D.
Qwerghzi off off off
Correct Answer
A. Qwerghzi on off onExplanation
Because strtr() ALWAYS looks for the longest possible match first, the 'o' => 'i' translation is not disrupted by the keys in 'off' => 'on' and 'on' => 'off' both starting with the character 'o'
Because strtr() will *NOT* try to replace stuff it has already worked on, the 'off' => 'on' translations don't translate the latter part of $str into 'on on on'Rate this question:
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- 2.
What is the output of the following code snippet? echo stristr('PHPzphpZPHPZfoo', 'Z');
- A.
ZphpZPHPZfoo
- B.
ZPHPZfoo
- C.
Zphpzphpzfoo
- D.
PhpZPHPZfoo
Correct Answer
A. ZphpZPHPZfooExplanation
stristr returns $haystack (parameter 1) from $needle onwards ($parameter 2) in a case insensitive fashion
strstr($haystack, $needle) is the case sensitive version of the functionRate this question:
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- 3.
What is the output of the following script? echo strlen('foo' . chr(0) . '1'), ', ', strlen(0x00);
- A.
5, 1
- B.
3, 0
- C.
3, 4
- D.
5, 0
- E.
4, 0
Correct Answer
D. 5, 0Explanation
0x00 (the number) when converted to a string has no length
Unlike in C, a null character won't terminate the string
Therefore D is correctRate this question:
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- 4.
What is the function of the ucfirst and lcfirst functions?
- A.
To make the string's first character uppercase or lowercase, respectively.
- B.
To make the string's first word uppercase or lowercase, respectively.
Correct Answer
A. To make the string's first character uppercase or lowercase, respectively.Explanation
Not many other options I could throw in there ;)
This one is just for review I suppose.Rate this question:
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- 5.
What is the output of the following? echo strcmp('first', 'second'), ", "; echo strcmp('44', '054'), ", "; echo strcmp('0x80', 'a'), ", "; echo strcmp('a', 'A');
- A.
-1, 1, -1, 1
- B.
-1, 0, -1, 1
- C.
1, 0, 1, -1
- D.
-1, -1, -1, -1
- E.
-1, -1, 1, -1
Correct Answer
B. -1, 0, -1, 1Explanation
strcmp Returns < 0 if str1 is less than str2 ; > 0 if str1 is greater than str2 , and 0 if they are equal.
//Order of precedence is: z > a, z > A, Z > 1 > 9 > 0Rate this question:
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- 6.
What is the output of: echo strspn('1800-555-5555789', '0123456789');
- A.
1
- B.
7
- C.
4
- D.
0
Correct Answer
A. 1Explanation
strspn is a pretty FUCKING RETARDED function and only checks the INITIAL SEGMENT of parameter 1 against all characters in parameter 2
If it was 1-800-555-whatever as the first parameter, then it would only return 1, because the INITIAL SEGMENT (containing characters from JUST parameter 2) is 1 character longRate this question:
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- 7.
What is the output of: echo strcspn('1-800-555-5555', '0');
- A.
2
- B.
3
- C.
5
- D.
0
Correct Answer
B. 3Explanation
B) is correct because strcspn returns the INITIAL SEGMENT of param1 that does NOT contain characters from param2
params 3 and 4 are start and length, respectively, which you can change the output of the function with.Rate this question:
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- 8.
What is the output of the following? echo strncasecmp('hello world', 'HelloWorld', 5), ', '; echo strcmp(44, 054), ', '; echo strcasecmp('xyz', 'ABC'), ', '; echo strncmp('0', 'Z', 1), ', '; echo strcmp('bb', 'aaaa');
- A.
1, 1, 1, -1, 1
- B.
0, 0, -1, -1, 1
- C.
1, 1, -23, 1, -1
- D.
-1, 0, -1, 1, -1
- E.
0, 0, -23, -1, 1
Correct Answer
E. 0, 0, -23, -1, 1Explanation
E) is correct because for the first one, strncasecmp compares str1 to str2 in a case-insensitive fashion, for the first 5 characters
For the second one, 054 (octal 44) is converted to decimal first, and then 44 == 44
For the third one, strcasecmp, xyz is converted to uppercase or ABC is converted to lowercase, and a is 23 positions away from x in ASCII
For the fourth one, 0 is compared to Z, for the first 1 characters, letters (even uppercase ones) take precedence over numbers
Finally, for the fourth one. Even though bb is shorter than aaaa, b is higher than a, so str1 is "greater"Rate this question:
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- 9.
What is the output of the following? echo substr("abcdef", -2), ', '; echo substr("abcdef", 4), ', '; echo substr("abcdef", -3, -1), ', '; echo substr("abcdef", 4, -2), ', '; echo substr("abcdef", 2, -1);
- A.
Cdef, ef, de, , cde
- B.
Ef, ef, de, e, cde
- C.
Ef, ef, de, , cdef
- D.
Ef, ef, de, , cde
- E.
Abcd, de, de, , cde
Correct Answer
D. Ef, ef, de, , cdeExplanation
string substr ( string $string , int $start [, int $length ] )
negative start starting $start positions from the end of the string
negative length means reading in characters $length positions before the end of the stringRate this question:
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- 10.
What is the output of the following? $text = 'This is a test'; echo substr_count($text, 'is'), ', ' echo substr_count($text, 'is', 3), ', '; echo substr_count($text, 'is', 3, 3), ', '; echo substr_count($text, 'is', 5, 10), ', '; $text2 = 'gcdgcdgcd'; echo substr_count($text2, 'gcdgcd');
- A.
2, 1, 0, WARNING, 1
- B.
2, 1, 0, , 1
- C.
2, 1, 0, WARNING, 2
- D.
2, 1, 0, , 2
- E.
2, 1, 1, WARNING, 1
Correct Answer
C. 2, 1, 0, WARNING, 2Explanation
C is correct
In the first one, there's 2 counts of $needle in $haystack
In the second one, by setting the offset to 3, there's now only one $needle in $haystack
In the third one, by setting the offset to 3 and length to 3, there's now only one $needle in $haystack (would be 's i')
In the fourth one, the offset + length exceed the length of the string, throwing a WARNING
In the fifth one, overlapping $needle's are NOT countedRate this question:
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- 11.
What is the output of the following? echo str_replace('@', ' [anti-spam] ', '[email protected]', $count); echo $count . ' values found.'; $phrase = "You should eat fruits, vegetables, and fiber every day."; $healthy = array("fruits", "vegetables", "fiber"); $yummy = array("pizza", "beer", "ice cream"); echo str_replace($healthy, $yummy, $phrase); $vowels = array("a", "e", "i", "o", "u", "A", "E", "I", "O", "U"); echo str_replace($vowels, "", "Hello World of PHP");
- A.
[email protected] 0 values replaced. You should eat pizza, beer, and ice cream every day. Hll Wrld f PHP
- B.
Email [anti-spam] example.com 1 values replaced. You should eat pizza, beer, and ice cream every day. Hll Wrld f PHP
- C.
Email [anti-spam] example.com 1 values replaced. You should eat pizza, beer, and ice cream every day. Hllo World of PHP
- D.
Email [anti-spam] example.com 1 values replaced. You should eat ice cream, beer, and pizza every day. Hll Wrld f PHP
Correct Answer
B. Email [anti-spam] example.com 1 values replaced. You should eat pizza, beer, and ice cream every day. Hll Wrld f PHPExplanation
B) is correct
mixed str_replace ( mixed $search , mixed $replace , mixed $subject [, int &$count ] )
@ is replaced with [anti-spam]
The fourth (optional) parameter $count (passed by reference) tells you how many values were counted
If both $search and $replace are passed in as arrays, each corresponding value is replaced
In the last one, all vowels are replaced with "" or an empty stringRate this question:
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- 12.
What is the output of: $string = "This is\tan example\nstring"; $tok = strtok($string, " \n\t"); while ($tok !== false) { echo "Word=$tok[br /]"; //pretend like [br /] is a real line break $tok = strtok(" \n\t"); }
- A.
This is an example string
- B.
This is an example string
Correct Answer
B. This is an example stringExplanation
In the token " \n\t" you'll notice there's a space, which is a valid delimiter, as such, B is correct, being split up across spaces as well as line breaks and tabsRate this question:
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- 13.
What is the output of the following? $haystack = "Hello World!'; $needle = 'lo'; echo strrchr($haystack, $needle);
- A.
3
- B.
4
- C.
Llo World!
- D.
Ld!
Correct Answer
D. Ld!Explanation
D) is correct because strrchr returns the part of the string which contains the last occurance of $needle in $haystack, up until the end of $haystack
Also, if $needle contains more than one characters, only the first one is used (unlike strstr)Rate this question:
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Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.
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Current Version
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Mar 21, 2023Quiz Edited by
ProProfs Editorial Team -
Jun 21, 2008Quiz Created by
Php123php
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