Java 百分比符号 (%) 是什么意思？
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What does the percentage symbol (%) mean?
提问by Mohamed Moamen
I ran into some code containing the %symbol inside the array argument.
我遇到了一些包含%数组参数中的符号的代码。
What does it mean and how does it work?
它是什么意思以及它是如何工作的？
Example:
例子：
String[] name = { "a", "b", "c", "d" };
System.out.println(name[4 % name.length]);
System.out.println(name[7 % name.length]);
System.out.println(name[50 % name.length]);
Output:
输出：
a
d
c
采纳答案by T.J. Crowder
That's the remainder operator, it gives the remainder of integer division. For instance, 3 % 2is 1because the remainder of 3 / 2is 1.
那是余数运算符，它给出整数除法的余数。例如，3 % 2是1因为其余3 / 2是1。
It's being used there to keep a value in range: If name.lengthis less than 4, 7, or 50, the result of % name.lengthon those values is a value that's in the range 0to name.length - 1.
它被用于在那里保持的值在范围：如果name.length小于4，7，或50，结果% name.length这些值是一个值，该值的范围为0至name.length - 1。
So that code picks entries from the array reliably, even when the numbers (4, 7, or 50) are out of range. 4 % 4is 0, 7 % 4is 3, 50 % 4is 2. All of those are valid array indexes for name.
因此，即使数字（4、7 或 50）超出范围，该代码也能可靠地从数组中选取条目。4 % 4是0，7 % 4是3，50 % 4是2。所有这些都是name.
Complete example (live copy):
完整示例（实时复制）：
class Example
{
public static void main (String[] args) throws java.lang.Exception
{
String[] name = { "a" , "b" , "c" , "d"};
int n;
n = 4 % name.length;
System.out.println(" 4 % 4 is " + n + ": " + name[n]);
n = 7 % name.length;
System.out.println(" 7 % 4 is " + n + ": " + name[n]);
n = 50 % name.length;
System.out.println("50 % 4 is " + n + ": " + name[n]);
}
}
Output:
输出：
4 % 4 is 0: a 7 % 4 is 3: d 50 % 4 is 2: c
回答by GhostCat
Simple: this is the modulo, or to be precise the remainderoperator.
简单：这是modulo，或者准确地说是余数运算符。
This has nothing to do with arrays per se. It is just a numerical computation on the value that gets used to compute the array index.
这与数组本身无关。它只是对用于计算数组索引的值进行数值计算。
