该章节第二题程序没问题，但不懂为什么
5.1
#include<stdafx.h>
#include <iostream>
using namespace std;
int main()
{
int max, min;
long long sum=0;
cout << "enter the max number: ";
cin >> max;
cout << "enter the min number; ";
cin >> min;
for (int i = max ; i >= min; i--)
sum = i + sum;
cout << "sum of the integer between max and min is: "<<sum<<endl;
return 0;
}
注意：for循环括号中的最后一条语句是在执行了循环体之后执行的
5.2
#include<stdafx.h>
#include <iostream>
#include<array>
const int Arsize = 100;
using namespace std;
int main()
{
array<long double, Arsize+1> factorials;
factorials[0] = factorials[1] = 1;
for (int i = 2; i <= Arsize; i++)
factorials[i]= i * factorials[i-1];
for (int i = 0; i <= Arsize; i++)
cout <<i <<"!= "<<factorials[i]<<endl;
//cout << "size of long double :" << sizeof(long double) << endl;
//cout << "size of long long:" << sizeof(long long) << endl;
return 0;
}
问题1：当定义array的时候用array<long double, Arsize> factorials;会出现array subscript out of range 的错误；若用 array<long double, Arsize+1> factorials;则可以正确显示结果；:
问题2：若将定义array行改为：array<long long, Arsize+1> factorials;即用long long类型的数据，计算出的阶乘结果出现错误，用sizeof（long long）和sizeof（long double）查看两种数据类型所占的字节数都显示的是8位，那么也就是说不是long long数据类型长度不够
5.3
#include<stdafx.h>
#include <iostream>
using namespace std;
int main()
{
int num;
long long sum=0;
cout << "enter a number:";
cin >> num;
while (num != 0)//不能用（num=cin.get）！=0作为测试条件，此时会将数字看做字符，将其ASCII码存入num，且会将输入完成的换行符作为下一个输入
{
sum = sum + num;
cout << "now the sum of the number you enter is:" << sum << endl;
cout << "enter next number: ";
cin >> num;
}
return 0;
}
5.4
#include<stdafx.h>
#include <iostream>
const int principal = 100;
const int D_intter_per_ye = 10;//Daphne每年利息都相同
const double C_interest = 0.05;//Cleo的利率，最好将数据类型定义为相同的，否则可能造成结果错误
using namespace std;
int main()
{
double Daphne=principal;
double Cleo = principal;
int year = 0;
while (Daphne>=Cleo)
{
year++;
Daphne =D_intter_per_ye+ Daphne;//直接用加上每年的利率，不用乘，运算速度更快
Cleo = Cleo * C_interest + Cleo;
}
cout << year << " years later Cleo's deposit lager than Daphne's\n"
<< "now,Cloe's deposit is: " << Cleo << endl
<< "now,Daphne's deposit is: " << Daphne << endl;
return 0;
}
5.5
#include<stdafx.h>
#include <iostream>
const int monthes = 12;
using namespace std;
int main()
{
const char *month[monthes] =
{
"Jan.","Feb.","Mar.","Apr.","May.","Jun.",
"Jul.","Aug.","Sept.","Oct.","Nov.","Dec"
};
int sales[monthes],sum=0;
for (int i = 0; i < monthes; i++)
{
cout << "enter the sales of " << month[i]<<": ";
cin >> sales[i];
sum = sum + sales[i];
}
cout << "Total sales this year is: " << sum;
return 0;
}
5.6
#include<stdafx.h>
#include <iostream>
const int monthes = 12;
const int years = 3;
using namespace std;
int main()
{
const char *month[monthes] =
{
"Jan.","Feb.","Mar.","Apr.","May.","Jun.",
"Jul.","Aug.","Sept.","Oct.","Nov.","Dec"
};
int sales[years][monthes];
int sum[years] = {0};
int total = 0;
for (int i = 0; i < years; i++)
{
cout << "enter No." << i + 1 << " year's sales of <C++ For Fools> each month\n";
for (int j = 0; j < monthes; j++)
{
cout << month[j] << ": ";
cin >> sales[i][j];
sum[i] = sum[i] + sales[i][j];
total = total + sales[i][j];
}
cout << "No." << i + 1 << "year's total sales is: " << sum[i]<<endl;
}
cout << " total sales of three years is: " << total;
return 0;
}
5.7
#include<stdafx.h>
#include <iostream>
#include<string>
using namespace std;
struct car
{
string manufacturer;
int prod_year;
};
int main()
{
int number;
cout << "How many cars do you wish to catalig? ";
cin >> number;
cin.get();//用于吸收输入数字后的换行符，否则将会将其认为下一个字符的输入
car *c_message= new car[number];//用new创建一个包含number个元素的car结构
for (int i = 0; i < number; i++)
{
cout << "Car #" << i + 1 << ":\n";
cout << "Please enter the make: ";
getline(cin,(c_message+i)->manufacturer);
cout << "Please enter the year made: ";
cin >> (c_message+i)->prod_year;
cin.get();//用于吸收输入数字后的换行符，否则将会将其认为下一个汽车的生产商名称
}
cout << "Here is your collection:\n";
for (int i = 0; i < number; i++)
{
cout << (c_message + i)->prod_year << " " << (c_message)->manufacturer<<endl;
}
return 0;
}
5.8
#include<stdafx.h>
#include <iostream>
using namespace std;
int main()
{
char words[20];//用于存放每次输入的单词，其值为最后一次输入的单词
int w_coun=0;
cout << "Enter words(to stop,type the word done):\n";
cin >> words;//输入的是单词，不需识别空格等，用cin就可以
while (strcmp(words, "done"))
{
w_coun++;
cin >> words;
}
cout << "You entered a total of " << w_coun << " words";
return 0;
}
5.9
#include<stdafx.h>
#include<iostream>
#include<string>
int main()
{
using namespace std;
string word;
int w_coun = 0;
cout << "Enter words(to stop,type the word done):\n";
cin >> word;//输入的是单词，不需识别空格等，用cin就可以
while (word!="done")
{
w_coun++;
cin >> word;
}
cout << "You entered a total of " << w_coun << " words";
return 0;
}
5.10
#include<stdafx.h>
#include<iostream>
int main()
{
using namespace std;
int row;
cout << "Enter number of rows: ";
cin >> row;
for (int i = 1; i <= row; i++)
{
for (int j = 1; j <= row - i; j++)
cout << ".";
for (int n = 1; n <= i; n++)
cout << "*";
cout << endl;
}
return 0;
}