How-to articles, tricks, and solutions about VARIABLES

"No X11 DISPLAY variable" - what does it mean?

"No X11 DISPLAY variable" is an error message that you might see when trying to run a Java program that uses the X Window System to display a graphical user interface (GUI).

accessing a variable from another class

To access a variable from another class in Java, you can use the following steps:

Best way to test for a variable's existence in PHP; isset() is clearly broken

In PHP, the isset() function is used to check if a variable has been set, meaning that it has been declared and is not equal to NULL.

Can't access global variable inside function

In PHP, if you want to access a global variable inside a function, you need to use the "global" keyword.

Changing a global variable from inside a function PHP

In PHP, global variables can be accessed and modified from within functions using the global keyword.

How can I print variable and string on same line in Python?

You can use the print() function in Python and use the + operator to concatenate a string and a variable.

How do I check if a variable exists?

In Python, you can check if a variable exists by using the globals() or locals() function to check if the variable is in the global or local namespace, respectively.

How do I put a variable’s value inside a string (interpolate it into the string)?

In Python, you can use the format() method or f-strings (available in Python 3.6 and above) to interpolate a variable's value into a string.

How do you know a variable type in java?

You can use the instanceof operator to determine the type of a variable in Java.

How to check if type of a variable is string?

You can use the type() function in Python to check the type of a variable.

How to include a PHP variable inside a MySQL statement

To include a PHP variable inside a MySQL statement, you need to use prepared statements with bound parameters.

Initializing multiple variables to the same value in Java

In Java, you can initialize multiple variables to the same value in a single statement by separating the variables with a comma.

Non-static variable cannot be referenced from a static context

In Java, a non-static (also known as an instance) variable or method can only be accessed from an instance of the class. A static (also known as a class) variable or method, on the other hand, can be accessed directly from the class, without the need for

Passing multiple variables to another page in url

There are several ways to pass variables from one PHP page to another.

PHP class: Global variable as property in class

You can use the global keyword to access a global variable inside a class.

php variable in html no other way than: <?php echo $var; ?>

Yes, that is one way to output the value of a PHP variable in HTML.

Setting public class variables

In PHP, you can set the value of a public class variable by using the assignment operator (=) after the variable name.

Variable might not have been initialized error

If you are getting the "variable might not have been initialized" error in Java, it means that you are trying to use a local variable that has not been assigned a value.

What is the naming convention in Python for variable and function?

In Python, variable and function names should be lowercase, with words separated by underscores.