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
– chessofnerd, Commented Jan 23, 2016 at 3:34
The unary - negates the value, while unary + just returns the original value (like multiplying by -1 and 1, respectively) — tmpearce
– tmpearce, Commented Jan 23, 2016 at 3:50

Daniel · Accepted Answer · 2016-01-23 03:42:03Z

4

+ 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.

answered Jan 23, 2016 at 3:42

Daniel

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TroyHaskin · Accepted Answer · 2016-01-23 03:43:10Z

2

Therefore,

3++4

is parsed to

plus(3,uplus(4))

answered Jan 23, 2016 at 3:43

TroyHaskin

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