Output in java (System.out.println())

Question

In Java :

System.out.println('c' + "Hello world" + 1);

gives

cHello world1

but

System.out.println('c' + 1 + "Hello world");

gives

100Hello world

i.e c is converted to its ASCII character.What rule does Java use for this?Can someone tell me the set of rules which I can follow to predict the output as this has become quite confusing for me.

If you add something to a string, it concatenates. That's the only time `+` concatenates. If you add a char to an int, it adds them numerically. — khelwood, Aug 09 '18 at 14:35
take a look to [this SO question](https://stackoverflow.com/questions/21317631/java-char-int-conversions) — juanlumn, Aug 09 '18 at 14:41
Well, not ASCII, UTF-16 (which is one of several character encodings for the Unicode character set). Java doesn't use ASCII. — Tom Blodget, Aug 09 '18 at 22:39

score 3 · Answer 1 · answered Aug 09 '18 at 14:37

The + operator becomes String concatenation operator only if the left-hand side is the String. Otherwise it remains the additive operator as per docs.

In your example 'c' is a char literal, which gets promoted to int during addition. Do note that c is 99, not 119 as in your example so the output is 100Hello world.

score 2 · Answer 2 · answered Aug 09 '18 at 14:37

because char in Java play two roles one as a String when you concatenate it with a String and the second as an int when you sum it with another numeric value.

So in your case :

System.out.println('c' + 1 + "Hello world");

Is equivalent to :

System.out.println(('c' + 1) + "Hello world");
                   ^       ^

where 'c' transform it to 99 :

System.out.println((99 + 1) + "Hello world");
                   ^^^    ^

For that you get :

100Hello world

Output in java (System.out.println())

2 Answers2