Why do multiple binary operators in a row work in MATLAB?

Question

Why is this a valid MATLAB query?

3++4

which evaluates to 7. Even more disturbing:

3+-5

evaluates to -2.

Given the following, I expected

3+*5

to evaluate to 15. Instead it throws an error.

Possible resolution related to thewaywewalk's answer to my previous question at Why is a trailing comma in a cell array valid Matlab syntax?

`3++++-++5` evaluates to -2. Guess `-` is 'stronger' than `+`? Weird... — chessofnerd, Jan 23 '16 at 03:34
The unary `-` negates the value, while unary `+` just returns the original value (like multiplying by -1 and 1, respectively) — tmpearce, Jan 23 '16 at 03:50

score 4 · Accepted Answer · answered Jan 23 '16 at 03:42

+ and - are not only binary operators, they are also unary operators.

Documentation:

For this reasons, the first two lines are evaluated as 3+(+4) and 3+(-5) but the last fails because no unary multiplication exists.

score 2 · Answer 2 · answered Jan 23 '16 at 03:43

2

Therefore,

3++4

is parsed to

plus(3,uplus(4))

answered Jan 23 '16 at 03:43

TroyHaskin

2 Answers2