PHP Interview Questions and Answers Paper three
1. Differentiate between variables and constants in PHP
| Variables | Constants |
|---|---|
| The value of a variable can be changed during the execution. | The constant value can’t be changed during script execution. |
| Variables require compulsory usage of the $ sign at the start. | No dollar sign ($) is required before using a constant. |
| It is possible to define a variable by simple assignment. | Constants can’t be defined by simple assignments. They are defined using the define() function. |
| The default scope is the current access scope. | Constants can be accessed throughout without any scoping rules. |
difference between $ and $$.
| $message | $$message |
|---|---|
| $message is a regular variable. | $$message is a reference variable. |
| It has a fixed name and stores a fixed value. | It stores data about the variable. |
| Data stored in $message is fixed. | The value of the $$message can change dynamically as the value of the variable changes. |
What is the difference between “echo” and “print” in PHP?
| echo | |
|---|---|
| echo can output one or more strings. | print can only output one string and it always returns 1. |
| echo is faster than print because it does not return any value. | print is slower compared to echo. |
| If you want to pass more than one parameter to echo, a parenthesis should be used. | Use of parenthesis is not required with the argument list. |
What is the difference between Session and Cookies ?
| Cookie | Session |
|---|---|
| Cookies are client-side files on a local computer that hold user information. | Sessions are server-side files that contain user data. |
| Cookies end on the lifetime set by the user. | When the user quits the browser or logs out of the programmed, the session is over. |
| It can only store a certain amount of info. | It can hold an indefinite quantity of data. |
| The browser’s cookies have a maximum capacity of 4 KB. | We can keep as much data as we like within a session, however there is a maximum memory restriction of 128 MB that a script may consume at one time. |
| Because cookies are kept on the local computer, we don’t need to run a function to start them. | To begin the session, we must use the session start() method. |
| Cookies are not secured. | Session are more secured compare than cookies. |
| Cookies stored data in text file. | Session save data in encrypted form. |
| Cookies stored on a limited data. | Session stored a unlimited data. |
| In PHP, to get the data from Cookies , $_COOKIES the global variable is used | In PHP , to set the data from Session, $_SESSION the global variable is used |
| We can set an expiration date to delete the cookie’s data. It will automatically delete the data at that specific time. | In PHP, to destroy or remove the data stored within a session, we can use the session_destroy() function, and to unset a specific variable, we can use the unset() function. |
What is the difference between GET and POST?
| S.No. | GET Request | POST Request |
|---|---|---|
| 1. | GET retrieves a representation of the specified resource. | POST is for writing data, to be processed to the identified resource. |
| 2. | It typically has relevant information in the URL of the request. | It typically has relevant information in the body of the request. |
| 3. | It is limited by the maximum length of the URL supported by the browser and web server. | It does not have such limits. |
| 4. | It is the default HTTP method. | In this, we need to specify the method as POST to send a request with the POST method. |
| 5. | You can bookmark GET requests. | You cannot bookmark POST requests. |
| 6. | It is less secure because data sent is part of the URL | It is a little safer because the parameters are not stored in browser history or in web server logs. |
| 7. | It is cacheable. | It is not cacheable. |
| 8. | For eg. GET the page showing a particular question. | For eg. Send a POST request by clicking the “Add to cart” button. |
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