c++Primer3.4.2节练习

练习3.24

#include "stdafx.h"
#include<iostream>
#include<string>
#include<vector>
//#include <ctype.h>
using namespace::std; 
int main()
{    
	int n;
	vector<int> num;
	decltype(num.size()) sum = 0;
	while (cin>>n)
	{
		num.push_back(n);
	}
	for (auto a=num.begin(),b = num.end()-1,m=a+(b-a+1)/2; a !=m;a++,b--)
	{
		sum = *a + *b;
		cout << sum << endl;
	}
	
	system("pause");
	return 0;

}

练习3.25

#include "stdafx.h"
#include<iostream>
#include<string>
#include<vector>
using namespace::std; 
int main()
{    
	vector<unsigned> score(11, 0);
	unsigned grade;
	
	while (cin>>grade)

	{
		auto a = score.begin();
		unsigned n = grade /10;
		a = a + n;
		++(*a);
	}
	for (auto a : score)
	{
		cout << a << endl;
	}
	system("pause");
	return 0;

}

练习3.26

迭代器之间没有定义两个迭代器之间的加法。