21. How can we encrypt the username and password using PHP?
1. base64_encode() 2. $encrypted_username=md5($username); $encrypted_password=md5($password);
3. $encrypted_username=sha1($username); $enncrypted_password=sha1($password);
22. What are the features and advantages of object-oriented programming?
standardization , re-usability , flexibility , less code
23. What are the differences between procedure-oriented languages and object-oriented languages?
In procedural programming the main emphasis is on procedure
while in object oriented the data is important part. on the same hand data is
more secured in object oriented program.
--Procedure Oriented Language: ----
PO Language is fully concentrates on Procedures/functions/methods.
It normally works as a sequence of actions as seen in flowchart or in any algorithm.
It follows top-down approach. It totally focuses on methods and not the data which is utilized by methods.
In PO languages if data is used by many methods then its declared as global data but there is a problem if we do that,
what is that, if we forgot or by mistake if we consume that data in some other method than it comes with problem.
Mostly these scenarios happen in large systems.
Example: COBOL, PASCAL, C, FORTRAN etc.
Object Oriented Language: ---
OO concepts says it think about data and bind that data and methods those are
manipulating that data into one entity nown as object and then utilize that object into system.
Example: C++, Java, C#, VB.Net etc.
There are some fundamental concepts of OO Language which a language has to follow
to be a truly OO language.
• OBJECT
• CLASS
• ABSTRACTION
• ENCAPSULATION
• DATA HIDING / INFORMATION HIDING
• INHERITANCE
• POLYMORPHISM
24. What is the use of friend function?
Friend functions
Sometimes a function is best shared among a number of different classes. Such functions can be declared either as member functions of one class or as global functions. In either case they can be set to be friends of other classes, by using a friend specifier in the class that is admitting them. Such functions can use all attributes of the class which names them as a friend, as if they were themselves members of that class.
A friend declaration is essentially a prototype for a member function, but instead of requiring an implementation with the name of that class attached by the double colon syntax, a global function or member function of another class provides the match.
class mylinkage
{
private:
mylinkage * prev;
mylinkage * next;
protected:
friend void set_prev(mylinkage* L, mylinkage* N);
void set_next(mylinkage* L);
public:
mylinkage * succ();
mylinkage * pred();
mylinkage();
};
void mylinkage::set_next(mylinkage* L) { next = L; }
void set_prev(mylinkage * L, mylinkage * N ) { N->prev = L; }
Friends in other classes
It is possible to specify a member function of another class as a friend as follows:
class C
{
friend int B::f1();
};
class B
{
int f1();
};
It is also possible to specify all the functions in another class as friends, by specifying the entire class as a friend.
class A
{
friend class B;
};
Friend functions allow binary operators to be defined which combine private data in a pair of objects. This is particularly powerful when using the operator overloading features of C++. We will return to it when we look at overloading.
25. What are the differences between public, private, protected, static, transient, final and volatile?
Public : access anyware in script
Protected: access only same class and access inherited class
Private: access only in same class
Final: restrict overriding with child class
26. What are the different types of errors in PHP?
1. Notices:
These are trivial, non-critical errors that PHP encounters while executing a script - for example,
accessing a variable that has not yet been defined. By default, such errors are not displayed
to the user at all - although you can change this default behaviour.
2. Warnings:
These are more serious errors - for example, attempting to include() a file which does not exist.
By default, these errors are displayed to the user, but they do not result in script termination.
3. Fatal errors: These are critical errors - for example, instantiating an object of a non-existent class,
or calling a non-existent function.These errors cause the immediate termination of the script,
and PHP?s default behaviour is to display them to the user when they take place.
27. What is the functionality of the function strstr and stristr?
strstr-finds the first occurence of a string inside another string (case-sensitive)
stristr-finds the first occurence of a string inside another string (case-insensitive).
28. What are the differences between PHP 3 and PHP 4 and PHP 5?
php3-functionalities are addes php4-zend engine is added php5-oops concepts are added
29. How can we convert asp pages to PHP pages?
Follow the steps below for converting ASP code into PHP.
In ASP, there is no need to put semicolon at the end of the each line, but a semicolon is required in PHP.
1. ASP syntax and PHP syntax
dim DescriptionText should be replaced by $ DescriptionText;
CStr(Request("section")) should be replaced by $_GET["section"]
if isnull(SectionID) or trim(SectionID) = "" then
//body
end if
in ASP is replaced by,
if($SectionID=="Null" || trim($SectionID)== "")
{
//body
}
in PHP
XMLFileName = BaseXMLPath & "about/" & SectionID & ".xml"
is replaced by,
$XMLFileName = $BaseXMLPath."about/".$SectionID.".xml";
XMLLocalFileName = Server.MapPath(XMLFileName)
In ASP Server.MapPath() function returns the physical location of the file name of an ASP file.
It returns something like this c:/apache/htdocs/foldername/filename.asp
We can use the following workaround below to get to the file location:
$root=$_SERVER['DOCUMENT_ROOT'];
$folder_file=$_SERVER['PHP_SELF'];
$filename=basename($_SERVER['PHP_SELF']);
$filepos=strpos($folder_file,$filename);
$folder=substr($folder_file,0,$filepos);
$file_location=$root.$folder;
$XMLLocalFileName=$file_location.$XMLFileName;
Now the ‘$XMLLocalFileName’ will return c:/apache/htdocs/foldername/filename.php
If you know an alternative simple solution you can share it here.
In ASP the logical operators used in conditions
are: &&-‘and’ ||- ‘or’
But in PHP it is replaced by && and ||
In ASP the array declaration is like this
Array()
In PHP it is replaced by array()
The ASP Request.ServerVariables("URL") function return folder name and filename.
In PHP its equivalent function is $_SERVER['PHP_SELF'];
In ASP the format for a function is
function functionName(argument)
//body of function
end function
In PHP the function format is:
function fuctionName(argument)
{
//body of function
}
In ASP the format for a for loop is:
for i=0 to sectionNode.length
//body of for loop
next
The PHP equivalent is:
for($i=0;$i<=count($sectionNode);$i++)
{
//body of for loop
}
In ASP Response.Write() function is used to display content in webpage and Response.End() is used to end the execution flow.
Its equivalent function used in PHP is echo and die.
In ASP Request.ServerVariables("HTTP_HOST") return the server name
Its equivalent function used in PHP is $_SERVER['HTTP_HOST']
the Request.Form() and Request.QueryString in ASP is same as $GET[‘’] and $_POST[‘’] in PHP
the instr() function return the integer value of find string in ASP, its equivalent function used in PHP is strpos()
the Int() function in ASP is replaced by intval() in PHP.
the Rnd() function in ASP is replaced by rand() in PHP
the Len() function in ASP is replaced by strlen() in PHP
The Mid() function in ASP returns a specified number of characters from a string, we used substr() function to return the same string in PHP.
the Replace() function in ASP is replaced by str_replace() in PHP .
the Trim() function in ASP is replaced by trim() in PHP.
2. Syntax for handling XML conversion.
Note that the syntax for PHP is with reference to PHP version 4 . It may be a slightly different in higher versions.
XML=load(XMLLocalFileName);
replaced by,
$XML=domxml_open_file($XMLLocalFileName);
documentElement
replaced by,
document_element()
SectionNode=RootNode->childNnodes(0);
replaced by,
$childnodes=$RootNode->child_nodes();
$SectionNode=$childnodes[1];
SectionNode->getAttribute("name");
replaced by,
$SectionNode->get_attribute("name");
DescriptionText =(DescriptionNode.text)
replaced by,
$DescriptionText =($DescriptionNode->get_content())
30. What is the functionality of the function htmlentities?
The htmlentities() function converts characters to HTML entities.
* ENT_COMPAT - Default. Encodes only double quotes
* ENT_QUOTES - Encodes double and single quotes
* ENT_NOQUOTES - Does not encode any quotes
$str = "Jane & 'Tarzan'";
echo htmlentities($str, ENT_COMPAT);
echo htmlentities($str, ENT_QUOTES);
echo htmlentities($str, ENT_NOQUOTES); ?>
the output
Jane & 'Tarzan'
Jane & 'Tarzan'
Jane & 'Tarzan'
