c primer plus 11章，复习13题

将字符串中的单词，倒序输出

输入：a apple a day

输出：day a apple a

#include
#include
#include
#define LIM 30
char * ffgets(char * str);
char * cp(char * str, char * ch);

int main()
{
    char word[LIM];
    char new[LIM];


   if ( fgets(word, LIM, stdin) && word[0] != '' && word[0] != 'n' )
    {
        cp(word, new);
    }
    return 0;
}

char * cp(char * str, char * ch)
{
    ffgets(str);
    int len = strlen(str);
    int t = len-1;
    int c, b = 0;     

    while (t >= 0)
    {
        if( !isalpha(str[t-1]) && !isalpha(str[t-1]) || t == 0 )  //判断是否是一个单词
        {
            c = t;
            while(isalpha(str[c]))
            {
                ch[b] = str[c];
                b++;
                c++;
            }
            ch[b++] = ' ';
        }     
        t--;
    }
    printf("n");
    puts(ch);
}

char * ffgets(char * str)     //去除换行号
{
    char * ch = str;
    int i = 0;
    while (str[i] != '' && str[i] != 'n')
        i++;
    if( str[i] == 'n')
        str[i] = '';
    else    
        while(getchar()  != 'n')
            continue;

    return ch;
}