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+21 votes
asked in CSC305 Fall 2022 by (1 point)

2 Answers

+12 votes
Best answer

The use of a ? denotes a ternary operator. Ternary operators are java's shorthand for if-else statements. You find them often used when you need to do a quick check before assigning one of two values to a variable, or for any other occasion where you'd have a simple bodied if-else statement returning or assigning something based on a condition. It's probably best compared like-so:

int value1 = 5;
int value2 = 10;
int biggestValue;

if(value1 > value2) {
    biggestValue = value1;
} else {
    biggestValue = value2;

Whilst the previous code snippet works perfectly fine, some people might find it easier or cleaner to rewrite the statement as a ternary. The same code above could be rewritten as a ternary:

int value1 = 5;
int value2 = 10;
int biggestValue = value1 > value2 ? value1 : value2;

This alternative takes the exact same steps as before: It evaluates whether value1 is greater than value2, assigning biggestValue the greatest of the two values. As you can see, the basic structure of a ternary operator is as follows:

someVariable = condition ? expressionIfTrue : expressionIfFalse;

just to clarify, ternary operations always return a value, so you are expected to do something with said value. It's not possible to, for instance, put two void method calls as your expressions. Beyond that caveat, they're a nifty holdover from C that can be useful in a pinch. The only thing is to of course ensure that you do not negatively impact your code's readability using it. Whilst shorter code is often nice, hiding complex operations in a single line can very easily sidetrack anyone trying to follow your work.

answered by (134 points)
selected by

Thorough explanation!

FYI, Python also has a ternary conditional operator, although it puts the operands in a different order:

text = "good" if score > 6 else "bad"

+7 votes

? acts like an if/else statement.

For example,

answer = (a = 2) ? 2 : 1;

means if a equals 2, then the answer is 2. Else, the answer is 1.

It could be rewritten as:

if (a = 2) {

 answer = 2;

} else {

 answer = 1;


answered by (1 point)

You mean (a == 2) with 2 equals signs...