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