C++ Primer 第五版第十章习题答案

书籍版本:2019年9月第一版;王刚 杨巨峰译;电子工业出版社

编译器 : win10  && VS2015

10.1

#include "stdafx.h"
#include 
#include 
#include 
#include 
using namespace std;

int main(int argc, char** argv)
{

	vector intVec = { 0,1,5,3,4,5,6,5 };
	auto result = find(intVec.begin(), intVec.end(), 5);
	string  s = (result == intVec.end()) ? "未找到" : "找到了";
	cout << s << *result << endl;

	int nCount = count(intVec.begin(), intVec.end(), 5);
	cout << "这个容器中有" << nCount << "个" << 5 << endl;

	system("pause");
	return 0;
}

10.2

#include "stdafx.h"
#include 
#include 
#include 
#include 
using namespace std;

int main(int argc, char** argv)
{

	vector strVec = { "can","you","find","the","right","word","right" };

	int nCount = count(strVec.begin(), strVec.end(), "right");
	cout << "这个容器中有" << nCount << "个right" << endl;

	system("pause");
	return 0;
}

10.3

#include "stdafx.h"
#include 
#include 
#include 
#include 
#include 

using namespace std;

int main(int argc, char** argv)
{

	vector intVec = { 0,11,22,33,44,55,66,77 };

	int nCount = accumulate(intVec.begin(), intVec.end(), 0);
	cout << "这个容器中所有元素和为" << nCount << endl;

	system("pause");
	return 0;
}

10.4

编译器可以编译通过,但可能会造成结果丢失;

#include "stdafx.h"
#include 
#include 
#include 
#include 
#include 

using namespace std;

int main(int argc, char** argv)
{

	vector intVec = { 0,11.8,22.8,33.8,44.8,55.8,66,77 };

	int nCount = accumulate(intVec.begin(), intVec.end(), 0);
	cout << "这个容器中所有元素和为" << nCount << endl;

	system("pause");
	return 0;
}

例如这段代码,正确结果为312,但是输出结果为308;

10.5

const char * 不支持 “==” 比较

10.6

#include "stdafx.h"
#include 
#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;

int main(int argc, char** argv)
{

	vector iVec = {1,2,3,4,5,6,7,8,9};
	cout << "初始值为:" << endl;
	for (auto i = iVec.begin(); i != iVec.end(); i++)
	{
		cout << *i << " ";
	}
	int n = iVec.size();
	fill_n(iVec.begin(), n, 0);
	cout << "替换后:" << endl;
	for (auto i = iVec.begin(); i != iVec.end(); i++)
	{
		cout << *i << " ";
	}

	system("pause");
	return 0;
}

10.7

a. 当list中元素个数大于一个时,因为vec是空的,程序会报错。当list中元素个数为0时,程序正常运行,但是list与vector中都是空的。

b. reserve只是预先分配内存空间大小,无法改变容器中元素数量,所以fill_n时还是会报错。

10.8

back_inserter是插入迭代器,是一种用来向容器中添加元素的迭代器。所以算法并没有改变容器元素个数。

10.9

#include "stdafx.h"
#include 
#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;

void elimDups(vector& words)
{
	cout << "初始容器为:" << endl;
	for (auto i = words.begin(); i != words.end(); i++)
	{
		cout << *i << " ";
	}
	sort(words.begin(), words.end());
	cout << endl;
	cout << "排序后容器为:" << endl;
	for (auto i = words.begin(); i != words.end(); i++)
	{
		cout << *i << " ";
	}
	auto end_unique = unique(words.begin(), words.end());
	cout << endl;
	cout << "重新排列后容器为:" << endl;
	for (auto i = words.begin(); i != words.end(); i++)
	{
		cout << *i << " ";
	}
	words.erase(end_unique, words.end());
	cout << endl;
	cout << "去重后容器为:" << endl;
	for (auto i = words.begin(); i != words.end(); i++)
	{
		cout << *i << " ";
	}
}

int main(int argc, char** argv)
{
	vector strVec = {"the","quick","red","fox","jumps","over","the","slow","red","turtle"};
	elimDups(strVec);

	system("pause");
	return 0;
}

10.10

因为算法本身不会执行容器的操作,他们只会运行于迭代器之上,执行迭代器的操作。

10.11

#include "stdafx.h"
#include 
#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;

void elimDups(vector& words)
{
	cout << "初始容器为:" << endl;
	for (auto i = words.begin(); i != words.end(); i++)
	{
		cout << *i << " ";
	}
	sort(words.begin(), words.end());
	cout << endl;
	cout << "排序后容器为:" << endl;
	for (auto i = words.begin(); i != words.end(); i++)
	{
		cout << *i << " ";
	}
	auto end_unique = unique(words.begin(), words.end());
	cout << endl;
	cout << "重新排列后容器为:" << endl;
	for (auto i = words.begin(); i != words.end(); i++)
	{
		cout << *i << " ";
	}
	words.erase(end_unique, words.end());
	cout << endl;
	cout << "去重后容器为:" << endl;
	for (auto i = words.begin(); i != words.end(); i++)
	{
		cout << *i << " ";
	}
}

bool isShorter(const string& s1, const string& s2)
{
	return s1.size() < s2.size();
}

int main(int argc, char** argv)
{
	vector strVec = {"the","quick","red","fox","jumps","over","the","slow","red","turtle"};
	elimDups(strVec);
	stable_sort(strVec.begin(), strVec.end(), isShorter);
	cout << endl;
	cout << "在按长度排序后:" << endl;
	for (auto &s : strVec)
	{
		cout << s << " ";
	}
	cout << endl;

	system("pause");
	return 0;
}

10.12


bool compareIsbn(Sales_data& sd1, Sales_data& sd2)
{
	return sd1.isbn() > sd2.isbn();
}

Sales_data在另一个工程里,懒得导入了,就是把上面的isshorter换成这个

10.13

#include "stdafx.h"
#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;

bool stringLengthBiggerThanFive(string& s)
{
	return s.size() >= 5;
}

int main(int argc, char** argv)
{
	vector strVec = {"the","quick","red","fox","jumps","over","the","slow","red","turtle"};
	cout << "初始时容器为:" << endl;
	for (auto &s : strVec)
	{
		cout << s << " ";
	}
	cout << endl;
	auto end_pare = partition(strVec.begin(), strVec.end(), stringLengthBiggerThanFive);
	strVec.erase(end_pare, strVec.end());
	cout << "在按长度是否大于5排序后:" << endl;
	for (auto &s : strVec)
	{
		cout << s << " ";
	}
	cout << endl;

	system("pause");
	return 0;
}

10.14

 

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