c++ primer plus(第6版)中文版 第五章编程练习答案

第五章编程练习答案

5.1输入2个整数，输出这2个之间（包括这两个）所有整数和

//5.1输入2个整数，输出这2个之间（包括这两个）所有整数和
#include <iostream>
using namespace std;

int main ()
{
int	n1,n2,sum=0;
cout << "输入区间：";
cin >> n1 >> n2;
if(n1>n2)
swap(n1,n2);
for (int i = n1; i <= n2; ++i)
sum += i;
cout << "[" << n1 << ", " << n2 << "]区间总和为" << sum << endl;
}

5.2用array和long double编写程序计算100!的和

//5.2用array和long double编写程序计算100!的和(array为c++11新加标准)
#include <iostream>
#include <array>
using namespace std;

int main ()
{
array<long double, 100>	factorials;
factorials[1] = factorials[0] = 1.0L;
for (unsigned i = 2; i <= 100; ++i)
factorials[i] = i * factorials[i-1];
for (unsigned i = 0; i <= 100; ++i)
cout << i << "! = "<< factorials[i] << endl;
}

5.3编写一个整数输入程序，每输入一个数，显示累计和，输入0停止

//5.3编写一个整数输入程序，每输入一个数，显示累计和，输入0停止
#include <iostream>
using namespace std;

int main ()
{
int n,sum = 0;
cout << "输入数字：";
do {
cin >> n;
sum += n;
cout << "累计和为：" << sum << endl;
} while (n != 0);
}

5.4Daphne以利息=0.10*原始存款存100美元，Cleo以利息=0.05*当前存款存100美元，求多少年后Cleo的财富将超过Daphne，并显示各自的价值

//5.4Daphne以利息=0.10*原始存款存100美元，Cleo以利息=0.05*当前存款存100美元，
//    求多少年后Cleo的财富将超过Daphne，并显示各自的价值
#include <iostream>
using namespace std;

int main ()
{
const double interest1 = 0.10,interest2 = 0.05;
const double Base = 100;
unsigned	years = 0;
double	DaphneTotal = Base, CleoTotal = Base;
cout << "年份" << "   Daphne" << "   " << "Cleo" << endl;
do {
DaphneTotal += interest1*Base;
CleoTotal += CleoTotal *interest2;
++years;
cout << years << ":     " << DaphneTotal << "     " << CleoTotal << endl;
} while (DaphneTotal >= CleoTotal);
cout << years << "年后，" << "Cleo的财富将超过Daphne，前者将达到$" << CleoTotal << "、后者$" << DaphneTotal << endl;
}

5.5编写一个程序输入每个月的书销售情况，最后显示一年总共销售。

//5.5编写一个程序输入每个月的书销售情况，最后显示一年总共销售。
#include <iostream>
#include <string>
using namespace std;

int main ()
{
unsigned	sales[12],sum=0;
const string months[] = {"1月", "2月", "3月", "4月", "5月", "6月", "7月", "8月", "9月", "10月", "11月", "12月"};
cout << "输入每月销售量。" << endl;
for (int i = 0; i < 12; ++i) {
cout << months[i] << "：";
cin >> sales[i];
}
for (int i = 0; i < 12; ++i) {
sum += sales[i];
}
cout << "全年销售总量" << sum << endl;
}

5.6在5.5的基础上，使用二维数组，计算3年每年的总共销售量和总量

//5.6在5.5的基础上，使用二维数组，计算3年每年的总共销售量和总量
#include <iostream>
#include <string>
using namespace std;

int main ()
{
unsigned	sales[3][12],sum=0,allsum=0;
const string months[] = {"1月", "2月", "3月", "4月", "5月", "6月", "7月", "8月", "9月", "10月", "11月", "12月"};
for (int i = 0; i < 3; ++i) {
cout << "输入第" << i + 1 << "年每月销售量。"<< endl;
for (int j = 0; j < 12; ++j) {
cout << months[j] << "：";
cin >> sales[i][j];
}
}
for (int i = 0; i < 3; ++i) {
for (int j = 0; j < 12; ++j) {
sum += sales[i][j];
}
allsum += sum;
cout << "第" << i + 1 << "年销售总量" << sum << endl;
}
cout << "3年销售总量" << allsum << endl;
}

5.7设计一个car结构（包括生产商和生产日期），先询问有几辆车，然后由用户输入，最后显示每个结构体内容

//5.7设计一个car结构（包括生产商和生产日期），先询问有几辆车，然后由用户输入，最后显示每个结构体内容
#include <iostream>
#include <string>
using namespace std;

struct Car
{
string maker;
unsigned	year;
};

int main ()
{
cout << "How many cars do you wish to catalog? ";
unsigned	num;
cin >> num;
cin.get();
Car*	CarsList = new Car [num];
for (unsigned i = 0; i < num; ++i) {
cout << "Car #" << i+1 << ": " << endl;
cout << "Please enter the make: ";
getline(cin, CarsList[i].maker);
cout << "Please enter the year made: ";
cin >> CarsList[i].year;
cin.get();
}
cout << "Here is your collection: " << endl;
for (unsigned i = 0; i < num; ++i)
cout << CarsList[i].year << " " << CarsList[i].maker << endl;
delete [] CarsList;
}

5.8输入一句话（以done结束），显示总共的词数（用char数组）

//5.8输入一句话（以done结束），显示总共的词数（用char数组）
#include <iostream>
#include <cstring>
using namespace std;

int main ()
{
cout << "Enter words (to stop, type the word done): ";
const char* const Done = "done";
int n=0;
char word[30];
while (strcmp(Done, word)){
n++;
cin >> word;
}
cout << "You entered a total of " << n-1 << " words." << endl;
}

5.9输入一句话（以done结束），显示总共的词数（用string对象）

//5.9输入一句话（以done结束），显示总共的词数（用string对象）
#include <iostream>
#include <cstring>
using namespace std;

int main ()
{
cout << "Enter words (to stop, type the word done): ";
string Done = "done";
int n=0;
string word;
while (Done!=word)
{
n++;
cin >> word;
}
cout << "You entered a total of " << n-1 << " words." << endl;
}

5.10输出图形，n行n列（第i（i<n）行有m-n个.和m个*）

//5.10输出图形，n行n列（第i（i<n）行有m-n个.和m个*）
#include <iostream>
using namespace std;

int main ()
{
int n;
cout << "Enter number of rows : " ;
cin >> n;
for(int i=1;i<=n;i++)
{
for(int j=1;j<=n;j++)
{
if(j<=n-i)  cout << ".";
else cout << "*";
}
cout << endl;
}
}