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Conditional expressions

Concept A conditional expression is a shorthand for an if-statement that assigns different values to one variable:

if (expression) var = value1; else var = value2;

This can be rewritten more concisely as:

var = (expression) ? value1 : value2;

The boolean-valued expression is evaluated: If the result is true, value1 is assigned to var ; if not, value2 is assign to var .

Program: Control02.java

// Learning Object Control02 //    conditional expressionspublic class Control02 {     public static void main(/*String[] args*/) {         int year = 2001;        int month = 2;         int days;        if (month == 2)             days = (year % 4 == 0) ? 28 : 29;        else if (month == 4 || month == 6 ||                 month == 9 || month == 11)            days = 30;         else            days = 31;         System.out.println(days);    } }

The program computes the number of days in a month taking leap years into account.

  • The variables are allocated and the first two, year and month , are given initial values.
  • The expression month == 2 evaluates to true, so the statement following the expression is executed. Jeliot will display Choosing then-branch to emphasize this.
  • The inner statement is an assignment statement with a conditional expression. The expression is evaluatedand its result is false, so the value after the colon is assigned to the variable. Jeliot will display Choosing else-branch .
  • The value of days is printed.

Exercise Complete the program with the correct computation for leap years: a year divisible by 100 is not a leap year unless itis divisible by 400.

Exercise Rewrite the entire if-statement as nested conditional expressions.

While loops

Concept A loop enables the execution of a statement (including a block of statements within braces) an arbitrary number of times.This statement is called the loop body . In a while loop, an expression is evaluated before each execution of the loop body,and loop body is executed if and only if the expression evaluates to true.

Program: Control03.java

// Learning Object Control03 //    while loopspublic class Control03 {     static int LIMIT = 100;    public static void main(/*String[] args*/) {        int factorial = 1;         int n = 1;        while (factorial < LIMIT) {             System.out.println(factorial);            n++;             factorial = factorial * n;        }     }}

This program prints all factorials less than LIMIT = 100 , namely, 1 ! = 1 , 2 ! = 2 , 3 ! = 6 , 4 ! = 24 .

  • The static constant and the two variables are allocated and initialized.
  • Then, and each time the keyword while is reached, the expression is evaluated. If it is true, execution proceeds with the loop body, andJeliot displays Entering the while loop the first time and Continuing the while loop on subsequent occasions.
  • The statements of the loop body are executed. They print the value of the current factorial, increment the counterand compute the new factorial; then, control returns to the while-expression.
  • If and when the expression evaluates to false, execution proceeds with the statement following the loop body.Jeliot displays Exiting the while loop .

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
Idrissa Reply
hello
Sherica
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
Kim
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Al
y=10×
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
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
Rachael Reply
yes
Asali
I'm not good at math so would you help me
Samantha
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)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
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
Prasenjit
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
Azam
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.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
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Source:  OpenStax, Learning objects for java (with jeliot). OpenStax CNX. Dec 28, 2009 Download for free at http://cnx.org/content/col10915/1.2
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