4 = 3
After executing that statement if you use
4 for something, it has the value of 3.
People explained this to me, with much giggling, saying ForTran would let you change the value of 4.
I now suspect this isn't strictly true (for one thing, 41 still has the expected value).
I think this is just an instance of ForTran's habit of creating variables whenever something is referenced as a variable.
If you call
COLOR(MAGENT) by mistake when trying to set the color to magenta,
and your program doesn't have a variable named
ForTran will helpfully create a variable by that name, and initialize it to zero for you.
A variant of that happened to me once while programming a Silicon Graphics machine,
due to the fact that some of the code had been compiled on a version of ForTran that truncated variable names
to six characters. As zero equated to black, my lovely double-buffered rotating 3-D Gouraud shaded figures
were completely invisible.
But I digress.
What's really happening in the
4 = 3 statement is that ForTran sees me using the symbol
4 as a variable. It obediently creates a variable named "4" and assigns it a value of 3. Then, when you refer to 4,
you get that variable, which shadows the original integer 4.
When I was little, my mom (who was a math teacher) instilled in me the differences between numbers, digits, and chalk dust. These differences are subtle but real, and occasionally come up and bite the unwary. When I got into typography, and added concepts of letters, characters, and glyphs, they fit right into the pantheon.