ssort.c

unix环境下实现的cmm语言编译器

/*ssort.c: 对文本行进行排序*/
int puts(char *s);
int printf(char *fmt, char *s);
char *strcpy(char *p, char *line);
char *malloc(int len);
int strcmp(char *s, char *d);

void qsort(void *lineptr[], int left, int right,
			int (*comp)(void *, void*));

char *lineptr[5000];
int readlines(char *lineptr[], int nlines);
void writelines(char *lineptr[], int nlines);
int getline(char *buf, int len);


int main(void)
{
	int nlines;

	if ((nlines = readlines(lineptr, sizeof lineptr)) >= 0) {
		qsort((void **)lineptr, 0, nlines - 1, (int (*)(void*,void*))strcmp);
		writelines(lineptr, nlines);
		return 0;
	} else {
		puts("error: input too big to sort\n");
		return 1;
	}
}

/*readlines:读取输入行*/
int readlines(char *lineptr[], int maxlines)
{
	int len, nlines;
	char *p, line[1000];

	nlines = 0;
	while ((len = getline(line, sizeof line)) > 0) {
		if (nlines >= maxlines)
			return -1;
		if ((p = malloc(len)) == (void *)0)
			return -1;
		line[len-1] = 0;
		strcpy(p, line);
		lineptr[nlines] = p;
		nlines = nlines + 1;
	}
	return nlines;
}

/*writelines:写输出行*/
void writelines(char *lineptr[], int nlines)
{
	int i = 0;

	while (i < nlines) {
		printf("%s\n", lineptr[i]);
		i = i + 1;
	}
}