Today, this article will walk you through the most commonly asked PHP interview questions and answers for freshers and experienced in the industry.
Since the data inside the single-quoted string is not parsed for variable substitution, it’s always a better idea speed-wise to initialize a string with single quotes, unless you specifically need variable substitution.
The first one is octal 23, the second is hex 23.
$var1 = 'Welcome to ';
$var2 = 'developerdiary.in;
$var 3 = $var1.$var2;
echo : is the most primitive of them, and just outputs the contents following the construct to the screen
print : is also a construct (so parentheses are optional when calling it), but it returns TRUE on successful output and FALSE if it was unable to print out the string. However, you can pass multiple parameters to echo, like:
and it will output the string “Welcome to Developerdiary!” print does not take multiple parameters. It is also generally argued that echo is faster, but usually the speed advantage is negligible, and might not be there for future versions of PHP.
printf : is a function, not a construct, and allows such advantages as formatted output, but it’s the slowest way to print out data out of echo, print and printf.
$message is a regular variable, which has a fixed name and fixed value, whereas a $$message is a reference variable, which stores data about the variable. The value of $$message can change dynamically as the value of the variable changes.
Magic constants start and end with double underscores and are predefined constants that change their value based on context and usage.
There are 9 magic constants in PHP:
__LINE__, __FILE__, __DIR__, __FUNCTION__, __CLASS__, __TRAIT__, __METHOD__, __NAMESPACE__, ClassName::class
The isset() function checks if the particular variable has a value other than NULL. The function returns Boolean value false if the variable is not set or return true if the variable is set. The function can check multiple values: isset(