Module 01 - Basic Building Blocks
Lesson 06 - Order of Operations
Different operations have different levels of priority. Multiplication, division, and modulus have higher priority than addition and subtraction, which have higher priority than assignment.
OnAssignAddition
{
_i = 10 + 2
_i
}
Click to run the above code in the Ghost Guides companion ghost.
The above function will output the integer 12. This is because 10 + 2 is run first, resulting in 12, and then the 12 is assigned to _i.
When there are multiple operations of the same priority, they are run from left to right.
OnAssignUninitializedVar
{
_i = _j = 10
_i
}
Click to run the above code in the Ghost Guides companion ghost.
The above function will not output anything. _j will contain the integer 10, but _i will be empty. This is because _i = _j is run first, but _j doesn’t contain anything at this time. Then, _j = 10 is run, and the value is assigned to _j.
You can give operations a higher priority level by surrounding them in parenthesis.
OnAssignResult
{
_i = (_j = 10)
_i
}
Click to run the above code in the Ghost Guides companion ghost.
The above function will output the integer 10. Both _i and _j will contain the integer 10. Since these are both assignment operations they have the same priority, but the parenthesis raise the priority level of _j = 10. Therefore, _j = 10 is run first, and _i = _j is run afterwards, assigning _i the value of _j.
The exact order depends on how deeply nested in parenthesis each operation is. For example, ((_i = 10)) would run before (_i = 10). However, note that this is also affected by the type of operation. So ((_i = 10)) runs after ((_i * 10)), because even though they are on the same level of parenthesis, multiplication takes priority over assignment.
Further Context
Order of operations can be tricky. Unfortunately, I don’t really have a good context example at this point, because most of what I do doesn’t involve operations this complicated. But, we will see order of operations come up again soon with something I do have experience with!
If you’ve got a good example of order of operations that I could show here, particularly with nesting in parenthesis, do get in touch.