分子量--c

#include <stdio.h>#include <ctype.h>int main(){char a[]="CHON";double b[4]={12.01,1.008, 16.00,14.01};int j,m;char s[20];scanf("%s",s);double sum1=0.0;int sum;int i=0;while(s[i]){for(j=0;j<4;j++){    if (s[i]==a[j])break;}i++;//先选好字母看其后面的数字，没有数字则为一sum=1;if (isdigit(s[i]))//判断其是否属于0-9阿拉伯数字sum=(s[i++]-'0');if (isdigit(s[i]))sum=sum*10+(s[i++]-'0'); sum1+=b[j]*sum;}printf("%f\n",sum1);return 0;}