【算法笔记】B1054 求平均值

atof(str)字符串转换浮点数

#include<bits/stdc++.h>
using namespace std;
bool isLegal(char *s){
    int i = 0;
    if(s[0]=='-'){
        i++;
    }
    for(;s[i]&&s[i]!='.';i++){
        if(!isdigit(s[i])){
            return false;
        }
    }
    if(s[i]=='.'){
        for(int j=i+1;s[j];j++){
            if(!isdigit(s[j])||j-i>2){
                return false;
            }
        }
    }
    double a = fabs(atof(s));
    if(a>1000.0){
        return false;
    }
    return true;
}
int main(){
    int n,nums = 0;
    double sum;
    char *x;
    x=(char *)malloc(sizeof(char));
    cin>>n;
    for(int i = 0; i < n; i++){
        scanf("%s", x);
        if(isLegal(x)){
            nums++;
            sum += atof(x);
        }else{
            printf("ERROR: %s is not a legal number
", x);
        }    
    }
    if(nums){
        if(nums==1){
            printf("The average of 1 number is %.2lf
",sum);
        }else{
            printf("The average of %d numbers is %.2lf
",nums,sum/nums);
        }
    }else{
        printf("The average of 0 numbers is Undefined
");
    }
    return 0;
}