PAT 1108 Finding Average

1108 Finding Average

The basic task is simple: given N real numbers, you are supposed to calculate their average. But what makes it complicated is that some of the input numbers might not be legal. A legal input is a real number in [−1000,1000] and is accurate up to no more than 2 decimal places. When you calculate the average, those illegal numbers must not be counted in.

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer N (≤100). Then N numbers are given in the next line, separated by one space.

Output Specification:

For each illegal input number, print in a line ERROR: X is not a legal number where X is the input. Then finally print in a line the result: The average of K numbers is Y where K is the number of legal inputs and Y is their average, accurate to 2 decimal places. In case the average cannot be calculated, output Undefined instead of Y. In case K is only 1, output The average of 1 number is Y instead.

Sample Input 1:

7
5 -3.2 aaa 9999 2.3.4 7.123 2.35

Sample Output 1:

ERROR: aaa is not a legal number
ERROR: 9999 is not a legal number
ERROR: 2.3.4 is not a legal number
ERROR: 7.123 is not a legal number
The average of 3 numbers is 1.38

Sample Input 2:

2
aaa -9999

Sample Output 2:

ERROR: aaa is not a legal number
ERROR: -9999 is not a legal number
The average of 0 numbers is Undefined

总结：这题就是使用 sscanf 和 sprintf 这两个函数（记住！！！）

sscanf() – 从一个字符串中读进与指定格式相符的数据
sprintf() – 字符串格式化命令，主要功能是把格式化的数据写入某个字符串中

代码：

#include 
#include 
using namespace std;

int main(){
    int n;
    scanf("%d",&n);
    
    double temp,sum=0;
    int cot=0;
    char a[50],b[50];
    for(int i=0;i1000){
            printf("ERROR: %s is not a legal number\n",a);
            continue;
        }
        sum+=temp;
        cot++;
    }
    sum/=cot;
    if(cot==0)  printf("The average of 0 numbers is Undefined\n");
    else if(cot==1) printf("The average of 1 number is %.2lf\n",sum);
    else printf("The average of %d numbers is %.2lf\n",cot,sum);
}

好好学习，天天向上！

我要考研！