Strings and numbers

[Justyna Wozniak]

Hi,
I am wondering on what theoretical basis this code:

    
System.out.println("" +5 + 6);   //1
System.out.println(5 + "" +6);   // 2
System.out.println(5 + 6 +"");   // 3
System.out.println(5 + 6);       // 4

produces the following output:

    
56
56
11
11

Why doesn't it produce:

    
56
56
56
11

?

[Henry Wong]

I believe addition has an associativity of from left to right -- so the expression is not a string addition until it encounters it first string to add, and then generates a string as a result.

Henry

[marc weber]

That's exactly right. (Uh, or maybe left. )

The + operator is syntactically left-associative, no matter whether it is later determined by type analysis to represent string concatenation or addition.

See JLS - 15.18.1.3 Examples of String Concatenation.