## !

! — Logical NOT operator.

## Description

Arithmetic operators perform operations of change-sign (negate), don't-change-sign, logical AND logical OR, add, subtract, multiply and divide. Note that a value or an expression may fall between two of these operators, either of which could take it as its left or right argument, as in

a + b * c.

In such cases three rules apply:

1. * and / bind to their neighbors more strongly than + and −. Thus the above expression is taken as

a + (b * c)

with * taking b and c and then + taking a and b * c.

2. + and bind more strongly than &&, which in turn is stronger than ||:

a && b - c || d

is taken as

(a && (b - c)) || d

3. When both operators bind equally strongly, the operations are done left to right:

a - b - c

is taken as

(a - b) - c

Parentheses may be used as above to force particular groupings.

## Syntax

`! a  (logical NOT; not audio-rate)`

where the argument a may be further expressions.

## Examples

Here is an example of the Logical NOT operator. It uses the file opnot.csd.

Example 32. Example of the opnot opcode.

See the sections Real-time Audio and Command Line Flags for more information on using command line flags.

```<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-odac    ;;;realtime audio out
; For Non-realtime ouput leave only the line below:
; -o opand.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

sr = 44100
ksmps = 32
nchnls = 2
0dbfs  = 1

instr 1

kval    randomh 0, 1.2, 20		;choose between 0 and 1.2
if !(kval >0 && kval<=.5) then		;3 possible outcomes
kval = 1
elseif !(kval >.5 && kval<=1) then
kval =2
elseif !(kval >1) then
kval =3
endif

printk2 kval				;print value when it changes
asig    poscil .7, 440*kval, 1
outs asig, asig

endin
</CsInstruments>
<CsScore>
f1 0 16384 10 1

i 1 0 5
e
</CsScore>
</CsoundSynthesizer>
```

Its output should include lines like these:

``` i1     1.00000
i1     2.00000
i1     1.00000
i1     2.00000
i1     1.00000
i1     2.00000
i1     1.00000
.....
```