C语言开发环境使用和数据类型，运算符，表达式

# include <stdio.h>
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 <stdio.h>
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 <stdio.h>
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; 
 }