习题3-2 分子量(Molar Mass)

#include <iostream>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
double gmol(char ch) {
    if(ch=='C') return 12.01;
    else if(ch=='H') return 1.008;
    else if(ch=='O') return 16.00;
    else if(ch=='N') return 14.01;
}
int num(char ch) {
    return (ch-'0');
}
using namespace std;

int main() {
    char s[1001];
    int len,i,n,t,j,l,k;
    double sum;
    while(scanf("%d",&k)!=EOF) {
        for(l=1; l<=k; l++) {

            while(scanf("%s",s)!=EOF) {
                len=strlen(s);
                sum=0;
                for(n=1,i=len-1; i>=0;) {
                    if(!isalpha(s[i])) {
                        t=1,n=0;
                        for(j=i; !isalpha(s[j])&&j>0; j--) {
                            n+=(num(s[j])*t);
                            t*=10;
                        }
                        i=j;
                    } else {
                        sum+=(gmol(s[i])*n);
                        for(j=i-1; isalpha(s[j])&&j>=0; j--) {
                            sum+=gmol(s[j]);
                        }
                        i=j;
                    }
                }
                printf("%.3f\n",sum);
            }
        }
    }
    return 0;
}
#include <iostream>
#include <stdio.h>
#include