实验2

 1 #include<stdio.h>
 2 #include<math.h>
 3 #include<time.h>
 4 #define N 5
 5 #define N1 397
 6 #define N2 476
 7 #define N3 21
 8 int main()
 9 {
10 int cnt ;
11 int random_major,random_no;
12 srand(time(NULL));
13 cnt = 0;
14 while (cnt<N)
15 {random_major =rand ()%2;
16 if (random_major)
17 {random_no=rand()%(N2-N1+1)+N1;
18 printf("20248329%04d\n",random_no);
19 }
20 else {random_no=rand()%N3+1;
21 printf("20248325%04d\n",random_no);
22 }
23 cnt++;}
24 return 0;

问题1，抽取计算机11到12班任意学号
问题2，抽取奇安信班任意学号
问题3，在计算机班中抽取4个任意学号

2 

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

 1 #include<stdio.h>
 2 #include<stdio.h>
 3 int main()
 4 {
 5     char ch;
 6     while (scanf("%c", &ch) != EOF)
 7         if (ch == 'y')
 8         {
 9             printf("wait a minute\n");
10             getchar();
11         }
12         else if (ch == 'g')
13         {
14             printf("go go go\n");
15             getchar();
16         }
17         else if (ch == 'r')
18         {
19             printf("stop!\n");
20             getchar();
21         }
22         else {
23             printf("something must be wrong\n"); getchar();
24         }
25     return 0;
26 }

 1 #include<stdio.h>
 2 int main()
 3 {
 4     double a;
 5     double b = 0;
 6     double max = 0;
 7     double min = 20000;
 8     while (scanf("%lf", &a) != EOF)
 9     {
10         if (a == -1)
11             break;
12         else if (a > max && a < min)
13         {
14             max = a;
15             min = a;
16         }
17         else if (a < min && a < max)
18         {
19             min = a;
20         }
21         else if (a > min && a > max)
22         {
23             max = a;
24         }b = a + b;
25     }
26     printf("今日累计消费：%.1f\n", b);
27     printf("今日最高消费：%.1f\n", max);
28     printf("今日最低消费：%.1f\n", min);
29     return 0;
30 }

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