cin成员函数

cin.fail();格式错误,未读取到预期参数值类型;指针不变,设置流状态为failbit;
cin.bad();输入发生毁灭性错误,导致io不稳定
cin.eof();遇到文件终止符
cin.good();
cin.get(char c);
cin.get(char c,int ,终止字符);
cin.getline(char *,int ,终止字符);
cin.ignore(int,终止字符)
char cin.peek() ;返回输入流下一个字符,流指针不变;
cin.putback(char c);将前面用cin读取到的单个字符,返回输入流中;



//#include <bits/stdc++.h>
#include <functional>
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <sstream>
#include <cstring>
#include <queue>
#include <vector>
#include <iterator>
#include <map>
#include <bitset>
#include <stack>
#include <deque>
#include <cmath>
#include <iomanip>
#include <forward_list>
#include <set>
#include <cmath>
#include <cctype>
#include <sstream>
#include <climits>
#include <list>
#include <typeinfo>
//INT_MAX 32 bit int
//LLONG_MAX 64 bit int
//LONG_MAX 64 bit int

using namespace std;

//#pragma comment(linker, "/STACK:3073741824")
#define memmin(a) memset(a,0,sizeof(a))
#define memmax(a) memset(a,0x3f,sizeof(a));
#define spr(n) fixed << setprecision(n)
#define endll '\n'
#define ifor(i, l, r) for (long long (i) = (l); (i) <= (r); ++(i))
#define rfor(i, r, l) for (long long (i) = (r); (i) >= (l); --(i))
#define fori(i,l,r) for(auto i=p;i!=p1;++i)
#define rfori(i,rl,rr) for(auto i=rl;i!=rr;++i)
#define coute cout<<'\n'
typedef long long ll;
typedef pair<int, int> P;
typedef unsigned long long ull;

template <class T, class Container = vector<T>,
          class Compare = less<typename Container::value_type> >
using priqueue = priority_queue<T,Container,Compare>;

#define start1
#ifndef start1
const int IINF = 0x3f3f3f3f;
const long long LINF = 0x3f3f3f3f3f3f3f3f;
const double EPS = 1.0e-9;
const long long MOD = 1e9 + 7;
const int MAX1 = 1e5 + 100;
const int MAX2 = 1e7 + 100;

#endif

#define start2
#ifndef start2

//__int128读取
void  read(ll& w) {
	w=0;
	ll f = 1;
	char ch = getchar();
	while (ch < '0' || ch > '9') {
		if (ch == '-')
			f = -1;
		ch = getchar();
	}
	while (ch <= '9' && ch >= '0') {
		w = w * 10 + ch - '0';
		ch = getchar();
	}
}

void print128(ll x) {
	if (x < 0) {
		putchar('-');
		x = -x;
	}
	if (x > 9)print128(x / 10);
	putchar(x % 10 + '0');
}

#endif

#define start
#ifndef start3
template<typename container>
void _print(container &a2) {
	for (auto i = a2.begin(); i != a2.end(); i++) {
		if (i == a2.begin()) cout << *i;
		else
			cout << " " << *i;
	}
}

template<typename T1>
auto _print(T1 a1, ll l, ll r) ->void {
	for (ll i = l; i <= r; ++i) {
		if (i == l) cout << a1[i];
		else cout << " " << a1[i];
	}
}
#endif
map<char,double>das;

int main(int argv,char** argc) {
//	ios::sync_with_stdio(false);
//	cin.tie(0);
//	cout.tie(0);
	das['C']=12.01,das['H']=1.008,das['O']=16.00,das['N']=14.01;
	int t;
	cin>>t;
	getchar();
	while(t--) {
		double sum{};
		char c;
		while(cin.get(c)&&c!='\n') {
//			cout<<c<<endl;
			if(isdigit(cin.peek())) {
				int x;
				cin>>x;
				sum+=x*das[c];
			}else{
				sum+=das[c];
			}
		}
		cout<<spr(3)<<sum<<endl;
	}
	return 0;
}

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有工作后先养猫:太好了,是超时空战警,我们有救了😋
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