# include <stdio.h>

int main()

{

char ch;

printf("输入一个字符:\n");

scanf("%c",&ch);

if(ch>='a'&&ch<='z')

ch=ch-'a'+'A';

printf("%c\n",ch);

return ;

}

#include <stdio.h>

int main() {

int days;

printf("输入一个整数: \n");

scanf("%d",&days);

if(days>=&&days<=)

printf("workdays, fighting\n");

else if(days==||days==)

printf("weekend, relax~\n");

else

printf("Ooops, not in 1~7\n");

return ;

}

//关系运算和逻辑运算

# include<stdio.h>

int main()

{

    int a=,b=,c=;

    printf("%d,%d,%d,%d\n",a==b&&a==c,a!=b&&a!=c,a>=b&&a>=c,a<=b&&a<=c);

    printf("%d,%d\n",a<=b||a>=c,a==b||b==c);

    printf("%d,%d,%d,%d\n",!(a==b),!(a>=b),!(a>=c),!(a<=b));

    return ;

 } 

/*Thhis is first C program*/

# include<stdio.h>

int main()

{

    printf("headbchsajhcuiknlxkns");

    return ;

}

/*求两个整数的乘积*/

# include<stdio.h>

int product(int,int);

int main(void)

{

    int x,y,s;

    scanf("%d %d",&x,&y);

    s=product(x,y);

    printf("The mul is:%d",s);

    return ;

 }

 int product(int a,int b)

 {

    int mul;

    mul=a*b;

    return mul;

 }

# include <stdio.h>

int main()

{

  int x;

  printf("输入一个整数: \n");

  scanf("%d",&x);

  if(x%==)

  printf("是奇数");

else

  printf("是偶数");

  return ;

}

/*整数相除*/

# include<stdio.h>

int main()

{

    int a=,b=,c=,d,e,f;

    d=a/b*c;

    e=a*c/b;

    f=c/b*a;

    printf("d=%d,e=%d,f=%d\n",d,e,f);

    return ;

 } 

/*自加、自减运算*/

# include<stdio.h>

int main()

{

    int a=,b=;

    printf("a++=%d\n",a++);

    printf("a=%d\n",a);

    printf("++b=%d\n",++b);

    printf("b=%d\n",b);

    return ;

 }