java - 逗号运算符在 "eval()"中做什么？

Question

我正在尝试学习java，并且在旧的UIL练习测试中遇到了这段代码，但我无法弄清楚这部分代码在做什么。

d[i][j] = eval(d[i-1][j]+1
[i][j-1]+1, d[i-1][j-1] + cost); /* the commas confuse me, I don't know what to add to cost */

如果有帮助的话，这是完整的代码

private static int eval(int a, int b, int c) {
    int m;
    m = a;
    if (b < m)
        m = b;
    if (c < m)
        m = c;
    return m;
}

public static int comp(String s, String t) {

    int d[][];
    int n, m, i, j;
    char si, tj, cost;
    n = s.length();
    m = t.length();

    if (n == 0) {
        return m;
    }

    if (m == 0) {
        return n;
    }

    d = < * 1 >;

    for (i = 0; i <= n; i++) {
        d[i][0] = i;
    }

    for (j = 0; j <= m; j++) {
        d[0][j] = j;
    }

    for (i = 1; i <= n; i++) {

        si = s.charAt(i - 1);

        for (j = 1; j <= m; j++) {

            tj = t.charAt(j - 1);

            if (si == tj) {
                cost = 0;
            } else {
                cost = 1;
            }

            d[i][j] = eval(d[i - 1][j] + 1,
            d[i][j - 1] + 1, d[i - 1][j - 1] + cost);
        }
    }
    return d[n][m];
}

Answer 1

方法中的逗号用于分隔参数。

如您所见，eval 方法需要树参数

private static int eval (int a, int b, int c){

在您的代码示例中，您像这样调用它

        d[i][j] = eval(d[i - 1][j] + 1, //<-there is comma here in your code
        d[i][j - 1] + 1, d[i - 1][j - 1] + cost);

等于

d[i][j] = eval(d[i-1][j]+1, d[i][j-1]+1, d[i-1][j-1] + cost);

因此参数a将是d[i-1][j]+1的值，b = d[i][j-1]+1和c=d[i-1][j-1] + cost