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An introduction to unary positive and unary negative operators used in programming with details of C++ usage.

General discussion

Unary positive also known as plus and unary negative also known as minus are unique operators. The plus and minus when used with a constant value represent the concept that the values are either positive or negative. Let’s consider:

+5 + -2

We have three operators in this order: unary positive, addition, and unary negative. The answer to this expression is a positive 3. As you can see, one must differentiate between when the plus sign means unary positive and when it means addition. Unary negative and subtraction have the same problem. Let’s consider:

-2 - +5

The expression evaluates to negative 7. Let’s consider:

7 - -2

First constants that do not have a unary minis in front of them are assumed (the default) to be positive. When you subtract a negative number it is like adding, thus the expression evaluates to positive 9.

C++ code examples

The above examples work within the C++ programming language. What happens if we put a unary positive or unary negative in front of a variable or a named constant?

Negation – unary negative

The concept of negation is to take a value and change its sign, that is: flip it. If it positive make it negative and if it is negative make it positive. Mathematically, it is the following C++ code example, given that money is an integer variable with a value of 6:

-money

money * -1

The above two expressions evaluate to the same value. In the first line, the value in the variable money is fetched and then it’s negated to a negative 6. In the second line, the value in the variable money is fetched and then it’s multiplied by negative 1 making the answer a negative 6.

Unary positive – worthless

Simply to satisfy symmetry, the unary positive was added to the C++ programming language as on operator. However, it is a totally worthless or useless operator and is rarely used.  However don’t be confused the following expression is completely valid:

6 + +5

The second + sign is interpreted as unary positive. The first + sign is interpreted as addition.

money

+money

money * +1

For all three lines, if the value stored in money is 6 the value of the expression is 6. Even if the value in money was negative 77 the value of the expression would be negative 77. The operator does nothing, because multiplying anything by 1 does not change its value.

Possible confusion

Do not confuse the unary negative operator with decrement. Decrement changes the value in the variable and thus is an Lvalue concept. Unary negative does not change the value of the variable, but uses it in an Rvalue context. It fetches the value and then negates that value. The original value in the variable does not change.

Because there is no changing of the value associated with the identifier name, the identifier name could represent a variable or named constant.

Exercises

    Evaluate the following items involving unary positive and unary negative:

  1. +10 - -2
  2. -18 + 24
  3. 4 - +3
  4. +8 + - +5
  5. +8 + / +5

    Answers:

  1. 12
  2. 6
  3. 1
  4. It’s 3. Surprised, but it works. The middle plus sign is addition and the rest are unary positive or unary negative.
  5. Error, no operand between addition and division.
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Definitions

unary positive
A worthless operator almost never used.
unary negative
An operator that causes negation.
plus
Aka unary positive.
minus
Aka unary negative.

Questions & Answers

can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
ninjadapaul
20/(×-6^2)
Salomon
okay, so you have 6 raised to the power of 2. what is that part of your answer
ninjadapaul
I don't understand what the A with approx sign and the boxed x mean
ninjadapaul
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
Salomon
I'm not sure why it wrote it the other way
Salomon
I got X =-6
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
ninjadapaul
oops. ignore that.
ninjadapaul
so you not have an equal sign anywhere in the original equation?
ninjadapaul
Commplementary angles
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what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
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a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
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or infinite solutions?
Kim
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Al
y=10×
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if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
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rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
is it 3×y ?
Joan Reply
J, combine like terms 7x-4y
Bridget Reply
im not good at math so would this help me
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Asali
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what is the problem that i will help you to self with?
Asali
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
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. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
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China
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types of nano material
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I start with an easy one. carbon nanotubes woven into a long filament like a string
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many many of nanotubes
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what is nanomaterials​ and their applications of sensors.
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what is nano technology
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what is system testing?
AMJAD
preparation of nanomaterial
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Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
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AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
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how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
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can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
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the Beer law works very well for dilute solutions but fails for very high concentrations. why?
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Source:  OpenStax, Programming fundamentals - a modular structured approach using c++. OpenStax CNX. Jan 10, 2013 Download for free at http://cnx.org/content/col10621/1.22
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