20131003国庆作业例4-4,4-5,4-6.

4-4

运行结果1

结果2

#include<stdio.h>
int main(void)
{
    int i,m;

    printf("Enter a number:");
    scanf("%d",&m);
    for(i=2;i<=m/2;i++)
        if(m%i==0)
            break;
    if(i>m/2&&m!=1)
        printf("%d is a prime number!
",m);
    else
        printf("No!
");

    return 0;
}

4-5

#include<stdio.h>
int main(void)
{
    int mynumber=38;
    int count=0,yournumber;
    for(count=1;count<=5;count++){
        printf("Input your number:");
        scanf("%d",&yournumber);
        if(yournumber==mynumber){
            printf("Ok!you are right!
");
            break;
        }
        else
            if(yournumber>mynumber)
                printf("Sorry!your number is bigger than my number!
");
            else
                printf("Sorry!your number is smaller than my number!
");
    }
    printf("Game is over!
");

    return 0;
}

4-6

#include<stdio.h>
double fact(int n);
int main(void)
{
    int i;
    double sum;
    sum=0;
    for(i=1;i<=100;i++)
        sum=sum+fact(i);
    printf("1!+2!+...+100!=%e
",sum);

return 0;
}
double fact(int n)
{
    int i;
    double result;

    result=1;
    for(i=1;i<=n;i++)
        result=result*i;

    return result;
}