实验2

任务1：

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include <time.h>
 4 
 5 #define N 5
 6 #define N1 397
 7 #define N2 476
 8 #define N3 21
 9 
10 int main() {
11     int cnt;
12     int random_major, random_no;
13 
14     srand(time(NULL));
15 
16     cnt = 0;
17     while(cnt < N) {
18         random_major = rand() % 2;
19 
20         if(random_major) {
21             random_no = rand() % (N2 - N1 + 1) + N1;
22             printf("20248329%04d\n", random_no);
23         }
24         else {
25             random_no = rand() % N3 + 1;
26             printf("20248395%04d\n", random_no);
27         }
28 
29         cnt++;
30     }
31 
32     return 0;
33 }

 问题1：在397到476中取任意一个数

问题2：在1到21中任取一个数

问题3：在一定范围内随机生成5个学号

 1 #include <stdio.h>
 2 #include <math.h>
 3 
 4 int main() {
 5     double a, b, c;
 6     double delta, p1, p2; 
 7 
 8     while(scanf("%lf%lf%lf", &a, &b, &c) != EOF) {
 9         if(a == 0) {
10             printf("a = 0, invalid input\n");
11             continue;
12         }
13 
14         delta = b*b - 4*a*c;
15         p1 = -b/2/a;
16         p2 = sqrt(fabs(delta))/2/a;
17 
18         if(delta == 0)
19             printf("x1 = x2 = %.2g\n", p1);
20         else if(delta > 0)
21             printf("x1 = %.2g, x2 = %.2g\n", p1+p2, p1-p2);
22         else {
23             printf("x1 = %.2g + %.2gi, ", p1, p2);
24             printf("x2 = %.2g - %.2gi\n", p1, p2);
25         }
26     }
27 
28     return 0;
29 }

 任务3：

 1 #include <stdio.h>
 2 
 3 int main()
 4 {
 5     char a;
 6     while (scanf("%c", &a) != EOF)
 7     {
 8         getchar();
 9         if (a == 'r')
10             printf("stop!\n");
11         else if (a == 'g')
12             printf("go go go\n");
13         else if (a == 'y')
14             printf("wait a minute\n");
15         else
16             printf("something must be wrong\n");
17     }
18     return 0;
19 }

 任务4：

 1 #include <stdio.h>
 2 
 3 int main()
 4 {
 5     double m;
 6     double sum = 0;
 7     double max = 0;
 8     double min = 0;
 9     printf("输入今日开销，直到输入-1终止:\n");
10     while (scanf("%lf", &m) != EOF)
11     {
12         if (m == -1)
13         {
14             break;
15         }
16         else
17         {
18             sum += m;
19             if (m >= max)
20             {
21                 max = m;
22             }
23             else
24             {
25                 min = m;
26             }
27         }
28     }
29     printf("今日累计消费总额: %.2lf\n", sum);
30     printf("今日最高一笔开销: %.2lf\n", max);
31     printf("今日最低一笔开销: %.2lf\n", min);
32     return 0;
33 }

 任务5：

 1 #include <stdio.h>
 2 
 3 int main()
 4 {
 5     int a, b, c;
 6     while (scanf("%d %d %d", &a, &b, &c) != EOF)
 7     {
 8         if (a + b > c && b + c > a && c + a > b)
 9         {
10             if (a * a + b * b == c * c || a * a + c * c == b * b || b * b + c * c == a * a)
11             {
12                 printf("直角三角形\n");
13             }
14             else if (a == b && b == c)
15             {
16                 printf("等边三角形\n");
17             }
18             else if (a == b || b == c || a == c)
19             {
20                 printf("等腰三角形\n");
21             }
22             else
23             {
24                 printf("普通三角形\n");
25             }
26         }
27         else
28         {
29             printf("不能构成三角形\n");
30         }
31     }
32     return 0;
33 }

 任务6：

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include <time.h>
 4 
 5 int main()
 6 {
 7     srand(time(NULL));
 8 
 9     int lucky_day = rand() % 30 + 1;
10     int cnt = 0;
11     int i;
12     while (cnt < 3)
13     {
14         scanf("%d", &i);
15         if (i == lucky_day)
16         {
17             printf("猜中了\n");
18             cnt = 3;
19             return 0;
20         }
21         else if (i > lucky_day)
22         {
23             printf("晚\n");
24             cnt++;
25         }
26         else
27         {
28             printf("早\n");
29             cnt++;
30         }
31     }
32     printf("%d\n", lucky_day);
33     return 0;
34 }