Free online test of php and mysql exam questions-- Asked at different competitive exams
Free Online test your knowledge on php and mysql programming exams. Each questions immediate answer or explanation given below, just click View answer button and also have option of Hide Answer button to hide answer. In this given upto 100+ questions and shows answer or explanation under of each question.
Here all the questions and answers, most asked in different competitive exams and shows answers accordingly.
Q91. What is the difference between Reply-to and Return-path in the headers of a mail function?
Answer:
Reply-to: Reply-to is where to delivery the reply of the mail.
Return-path: Return path is when there is a mail delivery failure occurs then where to delivery the failure notification.
Return-path: Return path is when there is a mail delivery failure occurs then where to delivery the failure notification.
Q92. Explain about Type Juggling in php?
Answer:
PHP does not require (or support) explicit type definition in variable declaration; a variable’s type is determined by the context in which that variable is used. That is to say, if you assign a string value to variable $var, $var becomes a string. If you then assign an integer value to $var, it becomes an integer.
An example of PHP’s automatic type conversion is the addition operator ‘+’. If any of the operands is a float, then all operands are evaluated as floats, and the result will be a float.
Otherwise, the operands will be interpreted as integers, and the result will also be an integer. Note that this does NOT change the types of the operands themselves; the only change is in how the operands are evaluated.
$foo += 2; // $foo is now an integer (2)
$foo = $foo + 1.3; // $foo is now a float (3.3)
$foo = 5 + “10 Little Piggies”; // $foo is integer (15)
$foo = 5 + “10 Small Pigs”; // $foo is integer (15)
If the last two examples above seem odd, see String conversion to numbers.
If you wish to change the type of a variable, see settype().
If you would like to test any of the examples in this section, you can use the var_dump() function.
Note: The behavior of an automatic conversion to array is currently undefined.
Since PHP (for historical reasons) supports indexing into strings via offsets using the same syntax as array indexing, the example above leads to a problem: should $a become an array with its first element being “f”, or should “f” become the first character of the string $a? The current versions of PHP interpret the second assignment as a string offset identification, so $a becomes “f”, the result of this automatic conversion however should be considered undefined.
PHP 4 introduced the new curly bracket syntax to access characters in string, use this syntax instead of the one presented above:
An example of PHP’s automatic type conversion is the addition operator ‘+’. If any of the operands is a float, then all operands are evaluated as floats, and the result will be a float.
Otherwise, the operands will be interpreted as integers, and the result will also be an integer. Note that this does NOT change the types of the operands themselves; the only change is in how the operands are evaluated.
$foo += 2; // $foo is now an integer (2)
$foo = $foo + 1.3; // $foo is now a float (3.3)
$foo = 5 + “10 Little Piggies”; // $foo is integer (15)
$foo = 5 + “10 Small Pigs”; // $foo is integer (15)
If the last two examples above seem odd, see String conversion to numbers.
If you wish to change the type of a variable, see settype().
If you would like to test any of the examples in this section, you can use the var_dump() function.
Note: The behavior of an automatic conversion to array is currently undefined.
Since PHP (for historical reasons) supports indexing into strings via offsets using the same syntax as array indexing, the example above leads to a problem: should $a become an array with its first element being “f”, or should “f” become the first character of the string $a? The current versions of PHP interpret the second assignment as a string offset identification, so $a becomes “f”, the result of this automatic conversion however should be considered undefined.
PHP 4 introduced the new curly bracket syntax to access characters in string, use this syntax instead of the one presented above:
Q93.How can I embed a java programme in php file and what changes have to be done in php.ini file?
Answer:
There are two possible ways to bridge PHP and Java: you can either integrate PHP into a Java Servlet environment, which is the more stable and efficient solution, or integrate Java support into PHP. The former is provided by a SAPI module that interfaces with the Servlet server, the latter by this Java extension.
The Java extension provides a simple and effective means for creating and invoking methods on Java objects from PHP. The JVM is created using JNI, and everything runs in-process.
Example Code:
getProperty(‘java.version’) . ”; echo ‘Java vendor=’ . $system->getProperty(‘java.vendor’) . ”; echo ‘OS=’ . $system->getProperty(‘os.name’) . ‘ ‘ . $system->getProperty(‘os.version’) . ‘ on ‘ . $system->getProperty(‘os.arch’) . ‘ ‘; // java.util.Date example $formatter = new Java(‘java.text.SimpleDateFormat’, “EEEE, MMMM dd, yyyy ‘at’ h:mm:ss a zzzz”); echo $formatter->format(new Java(‘java.util.Date’)); ?>
The behaviour of these functions is affected by settings in php.ini.
Table 1. Java configuration options
Name
Default
Changeable
java.class.path
NULL
PHP_INI_ALL
Name Default Changeable
java.home
NULL
PHP_INI_ALL
java.library.path
NULL
PHP_INI_ALL
java.library
JAVALIB
PHP_INI_ALL
The Java extension provides a simple and effective means for creating and invoking methods on Java objects from PHP. The JVM is created using JNI, and everything runs in-process.
Example Code:
getProperty(‘java.version’) . ”; echo ‘Java vendor=’ . $system->getProperty(‘java.vendor’) . ”; echo ‘OS=’ . $system->getProperty(‘os.name’) . ‘ ‘ . $system->getProperty(‘os.version’) . ‘ on ‘ . $system->getProperty(‘os.arch’) . ‘ ‘; // java.util.Date example $formatter = new Java(‘java.text.SimpleDateFormat’, “EEEE, MMMM dd, yyyy ‘at’ h:mm:ss a zzzz”); echo $formatter->format(new Java(‘java.util.Date’)); ?>
The behaviour of these functions is affected by settings in php.ini.
Table 1. Java configuration options
Name
Default
Changeable
java.class.path
NULL
PHP_INI_ALL
Name Default Changeable
java.home
NULL
PHP_INI_ALL
java.library.path
NULL
PHP_INI_ALL
java.library
JAVALIB
PHP_INI_ALL
Q94. How To Turn On the Session Support?
Answer:
The session support can be turned on automatically at the site level, or manually in each
PHP page script:
· Turning on session support automatically at the site level: Set session.auto_start =1 in php.ini.
· Turning on session support manually in each page script: Call session_start()
· Turning on session support automatically at the site level: Set session.auto_start =1 in php.ini.
· Turning on session support manually in each page script: Call session_start()
Q95. Explain the ternary conditional operator in PHP?
Answer:
Expression preceding the ? is evaluated, if it’s true, then the expression preceding the : is
executed, otherwise, the expression following : is executed.
Q96.How To Read the Entire File into a Single String?
Answer:
If you have a file, and you want to read the entire file into a single string, you can use the
file_get_contents() function. It opens the specified file, reads all characters in the file, and
returns them in a single string.
Here is a PHP script example on how to file_get_contents():
Size of the file: 7116
Here is a PHP script example on how to file_get_contents():
$file = file_get_contents(“/windows/system32/drivers/etc/services”); print(“Size of the file: “.strlen($file).”\n”);This script will print:
Size of the file: 7116
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