1) Difference between interface and abstract class
2) How would you provide security to a web application?
3) Diff between call by value and call by reference
4) Multiple inheritance in PHP
True Multiple inheritance is not possible in PHP. However it can be simulated by a mix of extending a class + “implementing” multiple interfaces / “using” multiple traits.
5) Does PHP pass objects by reference or by value
Simple answer is by reference. If you pass object to a function and it gets modified inside the function the changed value will be visible outside the function too. However Just remember: pointers to objects, not objects themselves, are passed to functions. These pointers are COPIES of the original unless you use "&" in your parameter list to actually pass the originals. Only when you dig into the internals of an object will the originals change. So as such it can also be said that the object pointers are passed by value. Good explanations: https://www.php.net/manual/en/language.oop5.references.php https://stackoverflow.com/questions/879/are-php-variables-passed-by-value-or-by-reference
6) What is ob_start in PHP
7) Which Design Patterns have you worked with?
8) Difference between valid xml and well formed xml
8) Given a string “This is Bob who has been working since 2002 in this industry. Wow 2002.”
write a program to determine which words in this string are palindromes.
Output should be
“Bob”
“2002”
Things to remember while writing the solution:
1) lowercase the string while checking for palindrome
2) Remove fullstops,etc. Account for multiple spaces between words.
3) The string can contain multiple Bob or 2002. So use a hash table to store the palindromes which are found. So that if that word occurs again then you don’t have to process it again.
9) Given the following schema, write a query which will produce the given output:
GRADE
ID GRADE
1 A
2 B
3 C
STUDENT:
ID NAME
1 John
2 Matt
3 Allie
STUDENT_GRADES:
STUDENT_ID GRADE_ID
1 1
2 2
3 1
OUTPUT:
GRADE STUDENTS
A John, Allie
B Matt
C NULL
SELECT G.GRADE, GROUP_CONCAT(S.NAME)
FROM grade G
LEFT JOIN student_grade SG
ON G.ID = SG.grade_id
LEFT JOIN student S
ON S.ID = SG.student_id
GROUP BY G.GRADE