What does — do in Excel formulas?

Question

Trying to decipher some Excel formulas and I see some stuff like SUMPRODUCT(--Left(...)...)

What is the -- doing? Naturally seems like decrementing to me but couldn\

Answer 1

I've been using SUMPRODUCT for a while and have always used the * symbol instead of the --. I'm sure I asked the same question you've asked, but I can't remember the reason they gave me, but I was told that there wasn't really a need for --as sumproduct managed itself quite well without the it.

Anyway, =sumproduct(()*()*()*()) has always worked for me, and it's less confusing.