PTA 乙级 1054 求平均值 (20分) C/C++

 1 #include<iostream>
 2 #include<cstring>
 3 using namespace std;
 4 
 5 int main() {
 6     int n = 0, k = 0;
 7     float sum = 0;
 8     cin >> n;
 9     for (int i = 0; i < n; ++i) {
10         char s1[100], s2[100];                    //一定要定义足够大，否则会出现测试点2运行时错误
11         float num = 0.0;
12         cin >> s1;
13         sscanf(s1, "%f", &num);                    //将s1中浮点数写入num
14         sprintf(s2, "%.2f", num);                //num保留两位数字输出到s2
15         if (strncmp(s1, s2, strlen(s1)) == 0 && (num <= 1000 && num >= -1000)) {    //利用strncmp，防止读取s2中多余的0
16             sum += num;
17             k++;
18         }
19         else {
20             cout << "ERROR: " << s1 << " is not a legal number" << endl;
21         }
22     }
23     if (k == 0) cout << "The average of 0 numbers is Undefined";
24     else if (k == 1) printf("The average of 1 number is %.2f", sum / k);    //注意只有一个数字的情况
25     else printf("The average of %d numbers is %.2f", k, sum / k);
26     return 0;
27 }