# include 
     
      int main() {   int days;      printf("输入一个整数:\n");   scanf("%d",&days);   if(days>=1&&days<=5)     printf("workdays, fighting\n");   else if(days==6||days==7)     printf("weekend, relax~\n");   else    printf("Ooops, not in 1~7\n");       return 0;    }
     

# include 
     
      int main() {    char ch;        printf("输入一个字符:\n");    scanf("%c",&ch);    if(ch>=97&&ch<=122);    ch=ch-('a'-'A');     printf("%c\n",ch);       return 0;}
     

#include 
     
      int main() {    int x;        printf("输入一个整数:\n");    scanf("%d",&x);    if(x%2!=0)      printf("是奇数");    else      printf("是偶数");             return 0;  }
     

 判断星期的截图

 

小写字母转换成大写字母截屏

 

总结

好难啊，以后要好好用心学习