英文:
Does order of operators matter when using compound assignment in Java? (+= vs =+)
问题
我有这段测试代码，我想要检查 sum =+ value 是否等同于 sum = sum + value。在Java中，这样写是可以的。它可以编译并且在我的机器上运行。
public class sum {
public static void main(String[] args) {
int sum = 0;
int value = 5;
sum =+ value;
System.out.println(sum);
sum = 0;
sum = sum + value;
System.out.println(sum);
}
}
英文:
I have this test code and I am trying to check if sum =+ value is equal to sum = sum + value. In Java, is this acceptable? It compiles and runs on my machine.
public class sum {
public static void main(String[] args) {
int sum = 0;
int value = 5;
sum =+ value;
System.out.println(sum);
sum = 0;
sum = sum + value;
System.out.println(sum);
}
}
答案1
得分: 2
是的，这很重要。
没有=+ 运算符。实际上它是两个运算符 - =（赋值），然后是 +（一元加法）。
sum =+ value 可以写成 sum = (+value)，它只是等同于 sum = value。
另一方面，+= 是一个适用于加法的正确运算符，sum += value 的意思是 sum = sum + value。
英文:
Yes, it matters.
There is no =+ operator. It's, in fact, two operators - = (assignment), followed by + (unary plus).
sum =+ value could be written as sum = (+value), which just evaluates to sum = value.
On the other hand += is a proper operator using for addition sum += value means sum = sum + value.
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