//翻转字符串
//按char翻转字符串
void reverseByChar(char* begin,char* end){
    while (begin<end) {
        char temp = *begin;
        *begin = *end;
        *end = temp;
        begin++;
        end--;
    }
}

//按照word翻转字符转
void reverseByWord(char* str){
    char* begin = str;
    char* end;
    for (end = begin; *end!='\0'; end++);
    end--;
//    or
//    long lenth = strlen(str);
//    end = begin + lenth -1;
    reverseByChar(begin, end);
    
    while (begin<=end) {
        char* charEnd ;
        //find begin  find first not ' '
        for (; *begin==' '; begin++);
        //find charEnd  find first  ' '
        for (charEnd = begin; *charEnd!=' '&&charEnd<=end; charEnd++);
        charEnd--;
        reverseByChar(begin, charEnd);
        begin = ++charEnd;
    }
    
    NSLog(@"%s",str);
}