阅读busybox telnetd line[8] = "pqrstuvwxyzabcde"[i]算法

最近在看busybox中telnetd源码，发下在make_new_session-->xgetpty-->存在如下部分代码

	...
    strcpy(line, "/dev/ptyXX");

	for (i = 0; i < 16; i++) {
		line[8] = "pqrstuvwxyzabcde"[i];
		line[9] = '0';
		if (stat(line, &stb) < 0) {
			continue;
		}
		for (j = 0; j < 16; j++) {
			line[9] = j < 10 ? j + '0' : j - 10 + 'a';
			if (DEBUG)
				fprintf(stderr, "Trying to open device: %s\n", line);
			p = open(line, O_RDWR | O_NOCTTY);
			if (p >= 0) {
				line[5] = 't';
				return p;
			}
		}
	}
    ...

初看之下 “line[8] = "pqrstuvwxyzabcde"[i];”的用法真的是没看懂...其实很简单

		line[8] = "pqrstuvwxyzabcde"[i];
		line[9] = '0';

等价于

	char *LoopChar = "pqrstuvwxyzabcde";
	line[8] = LoopChar[i];
	line[9] = '0';