#include <stdio.h> 
int main() {
    int x;

    printf("输入一个整数: \n");
    scanf("%d",&x);
    if(x%2==1) 
        printf("是奇数");
    else
        printf("是偶数");
    return 0;
}

 

 

 

#include <stdio.h>

int main() {
    int days;

    printf("输入一个整数: \n");
    scanf("%d",&days);

    if(days<=5&&days>=1) 
        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-32;
    printf("%c\n",ch);
    return ；
}

作为新手很多东西不是很明白，需要多多学习