Why do println(measure + '"'); and println(measure + '\"'); add to measure, while using seperate statements prints correctly?

Question

to test myself in Java, I wrote up a program where I needed to display the contents of double[] measurements, containing: {8.0, 7.7474, 7.4949, 7.7474, 8.0, 7.7474, 7.4949, 7.7474, 8.0}. A simple enhanced for loop and a println() seems to work fine, but

for(double measure: measurements)
{
   System.out.println(measure + '"');
}

prints out 42, 41.7474, 41.4949, etc. Exactly 34 more than the value of measure. Changing the code to

for(double measure: measurements)
{
    System.out.println(measure + '\"');
}

prints out 18,17.7474, 17.4949, etc. Exactly 10 more than the correct value. It only prints correctly when the println statement is split into two lines:

System.out.print(measure);
System.out.println("\"");

Why is it that the first two examples add to the value of measure? I'm fairly new to programming, but it seems to me that they would all have worked because Java uses both apostrophes and quotes to declare a string. Why does splitting it into two statements work correctly while connotating the two add to the value of measure? Thanks!

`char` is treated like a unsigned short when used in arithmetic. — killjoy, Jun 18 '18 at 22:17
_Java uses both apostrophes and quotes to declare a string_ - That's just not true. — CollinD, Jun 18 '18 at 22:17
"Java uses both apostrophes and quotes to declare a string." Nope. — Louis Wasserman, Jun 18 '18 at 22:18
@CollinD Java uses single quotes `'` to denote `char` values. You cannot have multiple chars within single quotes. — killjoy, Jun 18 '18 at 22:18
I actually completely ignored everything after the -. Oh well. — killjoy, Jun 18 '18 at 22:22

klutt · Accepted Answer · 2018-06-18T22:21:18.033

1

It's because you are printing the result of the expression measure + '"'. At the moment, you're performing an addition between a double and a char. If you instead use " instead of ' it will work.

Like this: System.out.println(measure + "\"");

Another option is to first convert measure to a string. That's rarely the best alternative, but the whole gist here is that you need to know the types of the operands and what the resulting type of the operation will be. Addition between a double and a char will result in a double. Addition between a double (or int or char among others) and a String will result in a String.

edited Jun 18 '18 at 22:21

answered Jun 18 '18 at 22:18

klutt

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Or you could just write `measure + "\""`. – Louis Wasserman Jun 18 '18 at 22:18
I see. I just assumed that Java used apostrophes the same way as Python, I didn't know that `char`s could be added to doubles. – Jgdabble Jun 18 '18 at 22:30

score 0 · Answer 2 · answered Jun 18 '18 at 22:20

0

Apostrophes are used to declare char not String remember that. You can't have more than one char within single quotes.

Just do measure + "\""

answered Jun 18 '18 at 22:20

Sheshank S.

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Why do println(measure + '"'); and println(measure + '\"'); add to measure, while using seperate statements prints correctly?

2 Answers2