实验2

task1.c

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


#define N 5

int main()
{
    int number;
    int i;
    srand( time(0) );

    for(i = 0; i < N; ++i)
    {
       number = rand()%65 + 1;
       printf("20238331%04d\n", number);
       }
    system("pause");
    return 0;
}

问题1：得到1~65之间的一个随机数

问题2：一次输出5个学号

task2.c

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

int main()
{
    char n;
    
    while(scanf("%c",&n) != EOF){
    
    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;
    }
    getchar();
    }
    system("pause");
    return 0;

}

task3.c

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

int main()
{
    int lucky_day;
    int guess;
    int cnt;
    
    lucky_day = rand()%31+1;
    for(cnt = 0;cnt<3;++cnt){
    scanf("%d",&guess);
        
        if(guess == lucky_day)
            printf("哇，猜中了！\n");
        else if(guess < lucky_day)
            printf("你猜的日期早了，你的lucky_day还没到呢\n");
            else
            printf("你猜的日期晚了，你的lucky_day在前面哦\n");
            
        
                
    }
      if(guess != lucky_day)
      printf("次数用完了，偷偷告诉你，五月你的lucky_day是:%d\n",lucky_day);  
        
        
        return 0;
}

task4.c

#include<stdio.h>
int main(){
    int a,n ,i;
    
    double s;
    
    while(scanf("%d%d",&a,&n) != EOF){
    int e=a;
    s = 0.0;

    
    for(i=1;i<=n;i++)
    {
    s+=(double)i/e;    
    e = e*10 +a;
}
    printf("n = %d,a = %d,s = %lf",n,a,s);
    
}
    
    
    return 0;
}

task5.c

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

task6.c

#include <stdlib.h>

int main() {
    int n, i, k, j;
    printf("input n:");
    scanf("%d", &n);

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

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

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

实验总结：

1、学会使用switch多分支语句

2、知道如何得到一个随机数