include<stdio.h>

include<string.h>

int last_len(char *str)
{
int i = strlen(str) - 1; //数组最后一个元素下标
int N = 0;
char word = 0;
word = str[i];
while(word == ' ') //如果输入的字符串最后含有空格
{
i--;
word = str[i];
}
while(1)
{
word = str[i];
if(word == ' '||i < 0) //i<0是为了防止只输入一个单词，无法遇到空格
break;
i--;
N++;
}
return N;
}
int main()
{
int N;
char str[100];
printf("please input a string:\n");
gets(str);
printf("the last word lenth is N=%d\n",last_len(str));
return 0;
}