Q: What is
A: Its the scope resolution operator (double colon)
Q: What is the cause of this warning: 'Warning: Cannot modify header information - headers already sent', and what is a good practice to prevent it?
A: *Cause:* body data was sent, causing headers to be sent too.
Prevention: Be sure to execute header specific code first before you output any body data. Be sure you haven't accidentally sent out whitespace or any other characters.
Q: What is wrong with this query:
A: 1. It is vulnarable to SQL injection. Never use user input directly in queries. Sanitize it first. Preferebly use prepared statements (PDO) 2. Don't select all columns (*), but specify every single column. This is predominantly ment to prevent queries hogging up memory when for instance a BLOB column is added at some point in the future.
Q: What is wrong with this if statement:
A:
Q: What is the preferred way to write this if statement, and why?
A: The former, as it prevents accidental assignment of 5 to $someVar when you forget to use 2 equalsigns (
T_PAAMAYIM_NEKUDOTAYIM?A: Its the scope resolution operator (double colon)
Q: What is the cause of this warning: 'Warning: Cannot modify header information - headers already sent', and what is a good practice to prevent it?
A: *Cause:* body data was sent, causing headers to be sent too.
Prevention: Be sure to execute header specific code first before you output any body data. Be sure you haven't accidentally sent out whitespace or any other characters.
Q: What is wrong with this query:
"SELECT * FROM table WHERE id = $_POST[ 'id' ]"?A: 1. It is vulnarable to SQL injection. Never use user input directly in queries. Sanitize it first. Preferebly use prepared statements (PDO) 2. Don't select all columns (*), but specify every single column. This is predominantly ment to prevent queries hogging up memory when for instance a BLOB column is added at some point in the future.
Q: What is wrong with this if statement:
if( !strpos( $haystack, $needle ) ...?A:
strpos returns the index position of where it first found the $needle, which could be 0. Since 0 also resolves to false the solution is to use strict comparison: if( false !== strpos( $haystack, $needle )...Q: What is the preferred way to write this if statement, and why?
if( 5 == $someVar ) or if( $someVar == 5 )A: The former, as it prevents accidental assignment of 5 to $someVar when you forget to use 2 equalsigns (
$someVar = 5), and will cause an error, the latter won't.
really nice interview questions.....!!
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