c++primer6.3节练习

6.33

#include "stdafx.h"
#include "iostream"
#include "stddef.h"
#include "string"
#include<vector>
using namespace std;
//2018_7_29，递归主要思想：返回的还是原先的vector，但是迭代器加一。
vector<int> output(const vector<int> &s1, vector<int>::iterator iter);
int main()
{
	vector<int> v1;
	for (int i = 0;i != 5;++i)
		v1.push_back(i);
	auto beg = v1.begin();
	output(v1,beg);
	return 0;
}

vector<int> output(const vector<int> &s1,vector<int>::iterator iter)
{
	
	if (iter != s1.end())
	{
		cout << *iter << endl;
		return output(s1,iter + 1);
	}
	return {};
}

6.34

#include "stdafx.h"
#include "iostream"
#include "stddef.h"
#include "string"
#include<vector>
using namespace std;
//2018_7_29
int factorial(int val);
int main()
{
	cout<<factorial(5)<<endl;
	system("pause");
	return 0;
}

int factorial(int val)
{
	if (val!=0)
		return factorial(val - 1)*val;
	return 1;
}

6.42

#include "stdafx.h"
#include "iostream"
#include "stddef.h"
#include "string"
#include<vector>
using namespace std;
//2018年8月11日，练习6.42
string make_plural(size_t ctr, const string &word, char end = 's')
{
	return (ctr > 1) ? word + end : word;
}

int main() {
	cout << make_plural(2, "failure") << endl;
	system("pause");
	return 0;
}

6.56

#include "stdafx.h"
#include "iostream"
#include "stddef.h"
#include "string"
#include<vector>
using namespace std;
//2018年8月11日，练习6.42

int add(int a, int b)
{
	return a + b;
}

int minuss(int a, int b)
{
	return a - b;
}

int multiply(int a, int b)
{
	return a * b;
}

int divide(int a, int b)
{
	return a / b;
}

int main() {
	int func(int, int);
	int a, b;
	using funcp = int(*)(int, int);
	vector<funcp> vec;
	vec = {add,minuss,divide,multiply};
	for (auto &c : vec)
	{
		cout << c << endl;
	}
	system("pause");
	return 0;
}

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