实验2

实验任务1

#include<stdio.h>
#include <stdlib.h>
#include <time.h>

#define N 5
#define N1 374
#define N2 465
int main()
{
int number;
int i;
srand( time(0) );

for(i = 0; i < N; ++i) {
number = rand()%(N2 - N1 + 1) + N1;
printf("202383290376%04d\n", number);
} 
return 0;
}

实验任务2

#include<stdio.h>
int main()
{
char n;
while(scanf("%c",&n)!=EOF)
{
    getchar();
    switch(n)
    {
        case'r':printf("stop!\n");break;
        case'g':printf("go go go\n");break;
        case'y':printf("wait a minute\n");break;
        default:printf("something must be wrong\n");break;
    }
}
return 0;
}

实验任务3

#include<stdio.h>
#include<math.h>
#include<stdlib.h>
int main()
{
    int n,i,x;
    n=rand()%30;
    printf("gusee which day is your lucky day\n");
    for(i=1;i<=3;i++)
    {
    scanf("%d",&x);
    if(x==n)
    {
    printf("ok,it's your lucky day\n");
    break;
    }
    else{
        if(x>n)
        printf("late\n");
        else
        printf("early\n");
        
    }
if(i==3)
printf("the right answer is %d",n);

    }
    return 0;
}

实验任务4

#include<stdio.h>
#include<stdlib.h>
int main()
{
    int i,n,x,a;
    double s;
    while(scanf("%d%d",&n,&a)!=EOF){
    x=0;
    s=0;
    for(i=1;i<=n;i++)
    {
        x=x*10+a;
        s=s+1.0*i/x;
    }
    printf("n=%d,a=%d,s=%f\n",n,a,s);
    }
    return 0;
}

实验任务5

#include<stdio.h>
int main()
{
    int i,j,ans;
    for(i=1;i<=9;i++)
    {
        for(j=1;j<=i;j++)
        {
            ans=i*j;
            printf("%dx%d = %2d  ",j,i,ans);
            if(i==j)
            {
                printf("\n");
            }
        }
    }
    
    return 0;
}

实验任务6

#include<stdio.h>
int main()
{
    int n;
    scanf("%d",&n);
    int i,j,k;
    j=0;

    
    
        for(i=2*n-1;i>0;i=i-2){
        
        
        for(j=0;j<(2*n-i-1)/2;j++){
            printf("\t");}
        for(k=1;k<=i;k++){
        printf(" O \t");
        if(k==i)
        printf("\n");}
        for(j=0;j<(2*n-i-1)/2;j++){
            printf("\t");}
        for(k=1;k<=i;k++){
        printf("<H>\t");
        if(k==i)
        printf("\n");}
        for(j=0;j<(2*n-i-1)/2;j++){
            printf("\t");}
        for(k=1;k<=i;k++){    
        printf("I I\t");
        if(k==i)
        printf("\n");}
    }
    

    return 0;
}