I just need to add the numbers, right?

Computer Science Level 3

What is the output of the following code?

public class Challenge {
    public static void main(String[] args) {
        System.out.print(10 + 20 + "30" + 40 + 50) ;
    }
}

303090 1020304050 30304050 The code will not run. 10203090

1 solution

Jaydee Lucero
Aug 17, 2017

In Java, the addition operator "+" operates from left to right .

When applied to two numbers, they will be added arithmetically.
When applied to two strings, they will be concatenated .
When applied to a number and a string, the number will be "converted" to a string, and then be concatenated to the (other) string.

For this problem, this becomes $\begin{aligned} 10 + 20 + \text{"30"} + 40 + 50 &= 30 + \text{"30"} + 40 + 50\text{ (arithmetical addition)} \\ &= \text{"3030"} + 40 + 50\text{ (integer-string concatenation)} \\ &= \text{"303040"} + 50\text{ (integer-string concatenation)} \\ &= \boxed{\text{"30304050"}}\text{ (integer-string concatenation)} \end{aligned}$

Thanks.I am learning java and I didnot knew that integers will be converted to string for concatenation in some case

Saksham Jain - 3 years, 6 months ago

I just need to add the numbers, right?

1 solution

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