C++PrimerPlus（第6版）中文版第八章实例代码

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#include<iostream>
inline double square(double x)
{
return x * x;
}
int main()
{
using namespace std;
double a, b;
double c = 13.0;
a = square(5.0);
b = square(4.5 + 7.5);
cout << "a = " << a << ",b = " << b << "n";
cout << "c = " << c;
cout << ",C squared = " << square(c++) << "n";
cout << "Now c = " << c << "n";
system("pause");
return 0;
}

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#include<iostream>
int main()
{
using namespace std;
int rats = 101;
int &rodents = rats;
cout << "rats = " << rats;
cout << ",rodents = " << rodents << endl;
rodents++;
cout << "rats = " << rats;
cout << ",rodents = " << rodents << endl;
cout << "rats address = " << &rats;
cout << ",rodents address = " << &rodents << endl;
system("pause");
return 0;
}

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#include<iostream>
int main()
{
using namespace std;
int rats = 101;
int &rodents = rats;
cout << "rats = " << rats;
cout << ",rodents = " << rodents << endl;
cout << "rat address = " << &rats;
cout << ",rodents address = " << &rodents << endl;
int bunnies = 50;
rodents = bunnies;
cout << "bunnies = " << bunnies;
cout << ",rats = " << rats;
cout << ",rodents = " << rodents << endl;
cout << "bunnies address = " << &bunnies;
cout << ",rodents address = " << &rodents << endl;
system("pause");
return 0;
}

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#include<iostream>
void swapr(int &a, int &b);
void swapp(int *p, int *q);
void swapv(int a, int b);
int main()
{
using namespace std;
int wallet1 = 300;
int wallet2 = 350;
cout << "wallet1 = $" << wallet1;
cout << " wallet2 = $" << wallet2 << endl;
cout << "Using reference to swap contents:n";
swapr(wallet1, wallet2);
cout << "wallet1 = $" << wallet1;
cout << "wallet2 = $" << wallet2 << endl;
cout << "Using pointers to swap contents again:n";
swapp(&wallet1, &wallet2);
cout << "wallet1 = $" << wallet1;
cout << "wallet2 = $" << wallet2 << endl;
cout << "Trying to use passing by value:n";
swapv(wallet1, wallet2);
cout << "wallet1 = &" << wallet1;
cout << " wallet2 = $" << wallet2 << endl;
system("pause");
return 0;
}
void swapr(int &a, int &b)
{
int temp;
temp = a;
a = b;
b = temp;
}
void swapp(int *p, int *q)
{
int temp;
temp = *p;
*p = *q;
*q = temp;
}
void swapv(int a, int b)
{
int temp;
temp = a;
a = b;
b = temp;
}

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#include<iostream>
double cube(double a);
double refcube(double &ra);
int main()
{
using namespace std;
double x = 3.0;
cout << cube(x);
cout << " = cube of " << x << endl;
cout << refcube(x);
cout << "= cube of " << x << endl;
system("pause");
return 0;
}
double cube(double a)
{
a *= a * a;
return a;
}
double refcube(double &ra)
{
ra *= ra * ra;
return ra;
}

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#include<iostream>
#include<string>
struct free_throws
{
std::string name;
int made;
int attempts;
float percent;
};
void display(const free_throws &ft);
void set_pc(free_throws &ft);
free_throws &accumulate(free_throws &target, const free_throws &source);
int main()
{
free_throws one = { "Ifelsa Branch",13,14 };
free_throws two = { "Andor Knott",10,16 };
free_throws three = { "Minnie Max",7,9 };
free_throws four = { "Whily Looper",5,9 };
free_throws five = { "Long Long",6,14 };
free_throws team = { "Throwgoods",0,0 };
free_throws dup;
set_pc(one);
display(one);
accumulate(team, one);
display(team);
display(accumulate(team, two));
accumulate(accumulate(team, three), four);
display(team);
dup = accumulate(team, five);
std::cout << "Displaying team:n";
display(team);
std::cout << "Displaying dup after assignment:n";
display(dup);
set_pc(four);
accumulate(dup, five) = four;
std::cout << "Displaying dup after ill-advised assignment:n";
display(dup);
system("pause");
return 0;
}
void display(const free_throws &ft)
{
using std::cout;
cout << "Name: " << ft.name << 'n';
cout << "
Made: " << ft.made << 't';
cout << "Attempts: " << ft.attempts << 't';
cout << "Percent:" << ft.percent << 'n';
}
void set_pc(free_throws &ft)
{
if (ft.attempts != 0)
ft.percent = 100.0f * float(ft.made) / float(ft.attempts);
else
ft.percent = 0;
}
free_throws &accumulate(free_throws &target, const free_throws &source)
{
target.attempts += source.attempts;
target.made += source.made;
set_pc(target);
return target;
}

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#include<iostream>
#include<string>
using namespace std;
string version1(const string &s1, const string &s2);
const string &version2(string &s1, const string &s2);
const string &version3(string &s1, const string &s2);
int main()
{
string input;
string copy;
string result;
cout << "Enter a string:";
getline(cin, input);
copy = input;
cout << "Your string as entered:" << input << endl;
result = version1(input, "***");
cout << "Your string enhanced:" << result << endl;
cout << "Your original string:" << input << endl;
result = version2(input, "###");
cout << "Your string enhanced:" << result << endl;
cout << "Your original string:" << input << endl;
cout << "Resetting original string.n";
input = copy;
result = version3(input, "@@@");
cout << "Your string enhanced:" << result << endl;
cout << "Your original string:" << input << endl;
system("pause");
return 0;
}
string version1(const string &s1, const string &s2)
{
string temp;
temp = s2 + s1 + s2;
return temp;
}
const string &version2(string &s1, const string &s2)
{
s1 = s2 + s1 + s2;
return s1;
}
const string &version3(string &s1, const string &s2)
{
string temp;
temp = s2 + s1 + s2;
return temp;
}

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#include<iostream>
#include<fstream>
#include<cstdlib>
using namespace std;
void file_it(ostream &os, double fo, const double fe[], int n);
const int LIMIT = 5;
int main()
{
ofstream fout;
const char *fn = "ep-data.txt";
fout.open(fn);
if (!fout.is_open())
{
cout << "Can't open " << fn << endl;
exit(EXIT_FAILURE);
}
double objective;
cout << "Enter the focal lengh of your "
"telescope objectives in mm:";
cin >> objective;
double eps[LIMIT];
cout << "Enter the focal lengths,in mm,of " << LIMIT
<< " eyepieces:n";
for (int i = 0; i < LIMIT; i++)
{
cout << "Eyepiece #" << i + 1 << ":";
cin >> eps[i];
}
file_it(fout, objective, eps, LIMIT);
file_it(cout, objective, eps, LIMIT);
cout << "Donen";
system("pause");
return 0;
}
void file_it(ostream &os, double fo, const double fe[], int n)
{
ios_base::fmtflags initial;
initial = os.setf(ios_base::fixed);
os.precision(0);
os << "Focal length of objective:" << fo << " mmn";
os.setf(ios::showpoint);
os.precision(1);
os.width(12);
os << "f.1. eyepiece";
os.width(15);
os << "magnification" << endl;
for (int i = 0; i < n; i++)
{
os.width(12);
os << fe[i];
os.width(15);
os << int(fo / fe[i] + 0.5) << endl;
}
os.setf(initial);
}

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#include<iostream>
const int ArSize = 80;
char *left(const char *str, int n = 1);
int main()
{
using namespace std;
char sample[ArSize];
cout << "Enter a string:n";
cin.get(sample, ArSize);
char *ps = left(sample, 4);
cout << ps << endl;
delete[] ps;
ps = left(sample);
cout << ps << endl;
delete[] ps;
system("pause");
return 0;
}
char *left(const char *str, int n)
{
if (n < 0)
n = 0;
char *p = new char[n + 1];
int i;
for (i = 0; i < n&&str[i]; i++)
p[i] = str[i];
while (i <= n)
p[i++] = '';
return p;
}

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#include<iostream>
unsigned long left(unsigned long num, unsigned ct);
char * left(const char *str, int n = 1);
int main()
{
using namespace std;
char *trip = (char *)"Hawaii!!" ;
unsigned long n = 12345678;
int i;
char *temp;
for (i = 1; i < 10; i++)
{
cout << left(n, i) << endl;
temp = left(trip, i);
cout << temp << endl;
delete[] temp;
}
system("pause");
return 0;
}
unsigned long left(unsigned long num, unsigned ct)
{
unsigned digits = 1;
unsigned long n = num;
if (ct == 0 || num == 0)
return 0;
while (n /= 10)
digits++;
if (digits > ct)
{
ct = digits - ct;
while (ct--)
num /= 10;
return num;
}
else
return num;
}
char *left(const char *str, int n)
{
if (n < 0)
n = 0;
char *p = new char[n + 1];
int i;
for (i = 0; i < n&&str[i]; i++)
p[i] = str[i];
while (i <= n)
p[i++] = '';
return p;
}

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#include<iostream>
template<typename T>
void Swap(T &a, T &b);
int main()
{
using namespace std;
int i = 10;
int j = 20;
cout << "i,j = " << i << "," << j << ".n";
cout << "Using complier-generated int swapper:n";
Swap(i, j);
cout << "Now i,j = " << i << "," << j << ".n";
double x = 24.5;
double y = 81.7;
cout << "x,y = " << x << "," << y << ".n";
cout << "Using complier-generated double swapper:n";
Swap(x,y);
cout << "Now x,y = " << x << "," << y << ".n";
system("pause");
return 0;
}
template <typename T>
void Swap(T &a, T &b)
{
T temp;
temp = a;
a = b;
b = temp;
}

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#include<iostream>
template <typename T>
void Swap(T &a, T &b);
template<typename T>
void Swap(T *a, T *b, int n);
void Show(int a[]);
const int Lim = 8;
int main()
{
using namespace std;
int i = 10, j = 20;
cout << "i,j = " << i << "," << j << ".n";
cout << "Using complier-generated int swapper:n";
Swap(i, j);
cout << "Now i,j = " << i << "," << j << ".n";
int d1[Lim] = { 0,7,0,4,1,7,7,6 };
int d2[Lim] = { 0,7,2,0,1,9,6,9 };
cout << "Original arrays:n";
Show(d1);
Show(d2);
Swap(d1, d2, Lim);
cout << "Swapped arrays:n";
Show(d1);
Show(d2);
system("pause");
return 0;
}
template<typename T>
void Swap(T &a, T &b)
{
T temp;
temp = a;
a = b;
b = temp;
}
template<typename T>
void Swap(T a[], T b[], int n)
{
T temp;
for (int i = 0; i < n; i++)
{
temp = a[i];
a[i] = b[i];
b[i] = temp;
}
}
void Show(int a[])
{
using namespace std;
cout << a[0] << a[1] << "/";
cout << a[2] << a[3] << "/";
for (int i = 4; i < Lim; i++)
cout << a[i];
cout << endl;
}

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#include<iostream>
template<typename T>
void Swap(T &a, T &b);
struct job
{
char name[40];
double salary;
int floor;
};
template <> void Swap<job>(job &j1, job &j2);
void Show(job &j);
int main()
{
using namespace std;
cout.precision(2);
cout.setf(ios::fixed, ios::floatfield);
int i = 10, j = 20;
cout << "i,j = " << i << "," << j << ".n";
cout << "Using complier-generated int swapper:n";
Swap(i, j);
cout << "Now i,j = " << i << "," << j << ".n";
job sue = { "Susan Yaffee",73000.60,7 };
job sidney = { "Sidney Taffee",78060.72,9 };
cout << "Before job swapping:n";
Show(sue);
Show(sidney);
Swap(sue, sidney);
cout << "After job swapping:n";
Show(sue);
Show(sidney);
system("pause");
return 0;
}
template<typename T>
void Swap(T &a, T &b)
{
T temp;
temp = a;
a = b;
b = temp;
}
template<> void Swap<job>(job &j1, job &j2)
{
double t1;
int t2;
t1 = j1.salary;
j1.salary = j2.salary;
j2.salary = t1;
t2 = j1.floor;
j1.floor = j2.floor;
j2.floor = t2;
}
void Show(job &j)
{
using namespace std;
cout << j.name << ":$" << j.salary
<< " on floor " << j.floor << endl;
}

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#include<iostream>
template<typename T>
void ShowArray(T arr[], int n);
template<typename T>
void ShowArray(T *arr[], int n);
struct debts
{
char name[50];
double amount;
};
int main()
{
using namespace std;
int things[6] = { 13,31,103,301,310,130 };
struct debts mr_E[3] =
{
{"Ima Wolfe",2400.0},
{"Ura Foxe",1300.0},
{"Iby Stout",1800.0}
};
double *pd[3];
for (int i = 0; i < 3; i++)
pd[i] = &mr_E[i].amount;
cout << "Listing Mr.E's counts of things:n";
ShowArray(things, 6);
cout << "Listing Mr.E's debts:n";
ShowArray(pd, 3);
system("pause");
return 0;
}
template<typename T>
void ShowArray(T arr[], int n)
{
using namespace std;
cout << "Template An";
for (int i = 0; i < n; i++)
cout << arr[i] << ' ';
cout << endl;
}
template<typename T>
void ShowArray(T *arr[], int n)
{
using namespace std;
cout << "template Bn";
for (int i = 0; i < n; i++)
cout << *arr[i] << ' ';
cout << endl;
}

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#include<iostream>
template<class T>
T lesser(T a, T b)
{
return a < b ? a : b;
}
int lesser(int a, int b)
{
a = a < 0 ? -a : a;
b = b < 0 ? -b : b;
return a < b ? a : b;
}
int main()
{
using namespace std;
int m = 20;
int n = -30;
double x = 15.5;
double y = 25.9;
cout << lesser(m, n) << endl;
cout << lesser(x, y) << endl;
cout << lesser<>(m, n) << endl;
cout << lesser<int>(x, y) << endl;
system("pause");
return 0;
}