#include<stdio.h>
int main()
{
    printf("Hello world\n");
    printf("Linux迷 www.linuxmi.com");
    return 0;
}

#include<stdio.h>
int main()
{
int a,b;
printf("Enter two numbers:");
scanf("%d%d",&a,&b);
printf("Sum=%d difference=%d product=%d quotient=%d\n",a+b,a-b,a*b,a/b);
return 0;
}

#include<stdio.h>
#include<math.h>
int main()
{
    float r;
    float N=3.14;
    float s;
    //N*r*r;該行必須在輸入r值以后
    printf("請輸入該圓的半徑:");
    scanf("%f",&r);
        s=N*r*r;
    printf("%.7f\n",s);//輸出小數點后7位
    return 0;
}

#include<stdio.h>
int main()  
{
int a, b, c;
printf("\nEnter value of a, b & c : ");
scanf("%d %d %d", &a, &b, &c);
if ((a > b) && (a > c))
printf("\na is greatest\n");
if ((b > c) && (b > a))
printf("\nb is greatest\n");
if ((c > a) && (c > b))
printf("\nc is greatest\n");
return 0;
}

#include<stdio.h>
int main()
{
int n;
printf("Enter a number:");
scanf("%d",&n);
if(n%2==0)
{
printf("Number is even\n");
}
else
{
printf("Number is odd\n");
}
return 0;
}

#include <stdio.h>
int main()
{
int n,i;
printf("Enter a positive integer: ");
scanf("%d",&n);
printf("Factors of %d are: ", n);
for(i=1;i<=n;++i)
{
if(n%i==0)
printf("%d ",i);
}
  return 0;
}

#include <stdio.h>
int main()
{
int n, i, flag = 0;
printf("Enter a positive integer: ");
scanf("%d",&n);
for(i=2; i<=n/2; ++i)
{
// condition for nonprime number
if(n%i==0)
{
flag=1;
break;
}
}
if (flag==0)
printf("%d is a prime number.\n",n);
else
printf("%d is not a prime number.\n",n);
return 0;
}

#include<stdio.h>
int main()
{
int year;
printf("Enter a year: ");
scanf("%d",&year);
if(year%4 == 0)
{
if( year%100 == 0)
{
// year is divisible by 400, hence the year is a leap year
if ( year%400 == 0)
printf("%d is a leap year.\n", year);
else
printf("%d is not a leap year.\n", year);
}
else
printf("%d is a leap year.\n", year );
}
else
printf("%d is not a leap year.\n", year);
return 0;
}

#include<stdio.h>
int main()
{
int i,n,sum=0;
printf("Upto how many terms you want to find the sum:");
scanf("%d",&n);
for(i=1;i<=n;i++){
sum = sum + i;
}
printf("Sum is %d\n",sum);
return 0;
}

#include <stdio.h>
int main()
{
int n, i;
unsigned long long factorial = 1;
printf("Enter an integer: ");
scanf("%d",&n);
// show error if the user enters a negative integer
if (n < 0)
printf("Error! Factorial of a negative number doesn't exist.");
else
{
for(i=1; i<=n; ++i)
{
factorial *= i;              // factorial = factorial*i;
}
printf("Factorial of %d = %llu\n", n, factorial);
}
return 0;
}