“student a am i”的倒置

问题：如何实现student a am i转换成为i am a student？

解析：可将语句完全倒置，成为i ma a tneduts，再将逐个单词倒置，成为i am a student

#include <stdio.h>
#include <string.h>

void reverse_string(char *l, char *r)
{
	while (l < r)
	{
		char tmp = *l;
		*l = *r;
		*r = tmp;
		l++;
		r--;
	}
}
void reverse(char ch[], int len)
{
	int i = 0;
	char *ctmpl = ch;
	char *ctmpr = ch;
	while (ch[i])
	{
		if (ch[i] == ' ')
		{
			reverse_string(ctmpl, ctmpr-1);
			ctmpl = ++ctmpr;
		}
		else
		{
			ctmpr++;
		}
		i++;
	}
	reverse_string(ch, ch + len - 1);
}
int main()
{
	char ch[] = "student a am i";
	reverse(ch,strlen(ch));
	printf("%s\n", ch);
}