Setting the value of a global variable from inside a function

Question

I am trying to set the value of a global variable X from inside a function.

I want the value of this variable to change when the function is called. The function will also return the string "pass" when called.

Here is the code:

function[] := (
   X = 10;
   Return["pass"];
   );

However, when I set a new value for X in the function, then call the function

function[]

and then call X, I get the OLD value of X, implying that X was never changed.

How would I go about doing this?

Answer 1

Evaluate this in a new session with a clean notebook.

x = 42;
function[] := (
  x = 10;
  "pass"
  )

Note that you do not need to use Return. A Wolfram Language function always returns the last expression it evaluates.

Evaluate

Dynamic[x]

You should get the output 42, the current value of x. Now evaluate

function[]

You should get the output pass and the output below Dynamic[x] should change to 10. Dynamic is very useful for tracking the changes to global variables when debugging.