C++ primer plus(第六版)编程练习答案第3章处理数据

末蓝、 2024-03-24 08:31 79阅读 0赞

## 一、程序清单 ##

## limits.cpp ##

// limits.cpp -- some integer limits
    #include <iostream>
    #include <climits>              // use limits.h for older systems
    int main()
    {
    	using namespace std;
    	int n_int = INT_MAX;        // initialize n_int to max int value
    	short n_short = SHRT_MAX;   // symbols defined in climits file
    	long n_long = LONG_MAX;
    	long long n_llong = LLONG_MAX;
    
    	// sizeof operator yields size of type or of variable
    	cout << "int is " << sizeof(int) << " bytes." << endl;
    	cout << "short is " << sizeof n_short << " bytes." << endl;
    	cout << "long is " << sizeof n_long << " bytes." << endl;
    	cout << "long long is " << sizeof n_llong << " bytes." << endl;
    	cout << endl;
    
    	cout << "Maximum values:" << endl;
    	cout << "int: " << n_int << endl;
    	cout << "short: " << n_short << endl;
    	cout << "long: " << n_long << endl;
    	cout << "long long: " << n_llong << endl << endl;
    
    	cout << "Minimum int value = " << INT_MIN << endl;
    	cout << "Bits per byte = " << CHAR_BIT << endl;
    	// cin.get();
    	return 0;
    }

执行结果：

int is 4 bytes.
    short is 2 bytes.
    long is 4 bytes.
    long long is 8 bytes.
    
    Maximum values:
    int: 2147483647
    short: 32767
    long: 2147483647
    long long: 9223372036854775807
    
    Minimum int value = -2147483648
    Bits per byte = 8

## exceed.cpp ##

// exceed.cpp -- exceeding some integer limits
    #include <iostream>
    #define ZERO 0      // makes ZERO symbol for 0 value
    #include <climits>  // defines INT_MAX as largest int value
    int main()
    {
    	using namespace std;
    	short sam = SHRT_MAX;     // initialize a variable to max value
    	unsigned short sue = sam;// okay if variable sam already defined
    
    	cout << "Sam has " << sam << " dollars and Sue has " << sue;
    	cout << " dollars deposited." << endl
    		<< "Add $1 to each account." << endl << "Now ";
    	sam = sam + 1;
    	sue = sue + 1;
    	cout << "Sam has " << sam << " dollars and Sue has " << sue;
    	cout << " dollars deposited.\nPoor Sam!" << endl;
    	sam = ZERO;
    	sue = ZERO;
    	cout << "Sam has " << sam << " dollars and Sue has " << sue;
    	cout << " dollars deposited." << endl;
    	cout << "Take $1 from each account." << endl << "Now ";
    	sam = sam - 1;
    	sue = sue - 1;
    	cout << "Sam has " << sam << " dollars and Sue has " << sue;
    	cout << " dollars deposited." << endl << "Lucky Sue!" << endl;
    	// cin.get();
    	return 0;
    }

执行结果：

Sam has 32767 dollars and Sue has 32767 dollars deposited.
    Add $1 to each account.
    Now Sam has -32768 dollars and Sue has 32768 dollars deposited.
    Poor Sam!
    Sam has 0 dollars and Sue has 0 dollars deposited.
    Take $1 from each account.
    Now Sam has -1 dollars and Sue has 65535 dollars deposited.
    Lucky Sue!

## hexoct1.cpp ##

// hexoct1.cpp -- shows hex and octal literals
    #include <iostream>
    int main()
    {
        using namespace std;
        int chest = 42;     // decimal integer literal
        int waist = 0x42;   // hexadecimal integer literal
        int inseam = 042;   // octal integer literal
    
        cout << "Monsieur cuts a striking figure!\n";
        cout << "chest = " << chest << " (42 in decimal)\n";
        cout << "waist = " << waist << " (0x42 in hex)\n";
        cout << "inseam = " << inseam << " (042 in octal)\n";
    	// cin.get();
        return 0; 
    }

执行结果：

Monsieur cuts a striking figure!
    chest = 42 (42 in decimal)
    waist = 66 (0x42 in hex)
    inseam = 34 (042 in octal)

## hexoct2.cpp ##

// hexoct2.cpp -- display values in hex and octal
    #include <iostream>
    using namespace std;
    int main()
    {
    	using namespace std;
    	int chest = 42;
    	int waist = 42;
    	int inseam = 42;
    
    	cout << "Monsieur cuts a striking figure!" << endl;
    	cout << "chest = " << chest << " (decimal for 42)" << endl;
    	cout << hex;      // manipulator for changing number base
    	cout << "waist = " << waist << " (hexadecimal for 42)" << endl;
    	cout << oct;      // manipulator for changing number base
    	cout << "inseam = " << inseam << " (octal for 42)" << endl;
    	// cin.get();
    	return 0;
    }

执行结果：

Monsieur cuts a striking figure!
    chest = 42 (decimal for 42)
    waist = 2a (hexadecimal for 42)
    inseam = 52 (octal for 42)

## chartype.cpp ##

// chartype.cpp -- the char type
    #include <iostream>
    int main()
    {
    	using namespace std;
    	char ch;        // declare a char variable
    
    	cout << "Enter a character: " << endl;
    	cin >> ch;
    	cout << "Hola! ";
    	cout << "Thank you for the " << ch << " character." << endl;
    	// cin.get();
    	// cin.get();
    	return 0;
    }

执行结果：

Enter a character:
    M
    Hola! Thank you for the M character.

## morechar.cpp ##

// morechar.cpp -- the char type and int type contrasted
    #include <iostream>
    int main()
    {
    	using namespace std;
    	char ch = 'M';       // assign ASCII code for M to ch
    	int i = ch;          // store same code in an int
    	cout << "The ASCII code for " << ch << " is " << i << endl;
    
    	cout << "Add one to the character code:" << endl;
    	ch = ch + 1;          // change character code in ch
    	i = ch;               // save new character code in i
    	cout << "The ASCII code for " << ch << " is " << i << endl;
    
    	// using the cout.put() member function to display a char
    	cout << "Displaying char ch using cout.put(ch): ";
    	cout.put(ch);
    
    	// using cout.put() to display a char constant
    	cout.put('!');
    
    	cout << endl << "Done" << endl;
    	// cin.get();
    	return 0;
    }

执行结果：

The ASCII code for M is 77
    Add one to the character code:
    The ASCII code for N is 78
    Displaying char ch using cout.put(ch): N!
    Done

## bondini.cpp ##

// bondini.cpp -- using escape sequences
    #include <iostream>
    int main()
    {
    	using namespace std;
    	cout << "\aOperation \"HyperHype\" is now activated!\n";
    	cout << "Enter your agent code:________\b\b\b\b\b\b\b\b";
    	long code;
    	cin >> code;
    	cout << "\aYou entered " << code << "...\n";
    	cout << "\aCode verified! Proceed with Plan Z3!\n";
    	// cin.get();
    	// cin.get();
    	return 0;
    }

执行结果：

Operation "HyperHype" is now activated!
    Enter your agent code:42007007
    You entered 42007007...
    Code verified! Proceed with Plan Z3!

## floatnum.cpp ##

// floatnum.cpp -- floating-point types
    #include <iostream>
    int main()
    {
    	using namespace std;
    	cout.setf(ios_base::fixed, ios_base::floatfield); // fixed-point
    	float tub = 10.0 / 3.0;     // good to about 6 places
    	double mint = 10.0 / 3.0;   // good to about 15 places
    	const float million = 1.0e6;
    
    	cout << "tub = " << tub;
    	cout << ", a million tubs = " << million * tub;
    	cout << ",\nand ten million tubs = ";
    	cout << 10 * million * tub << endl;
    
    	cout << "mint = " << mint << " and a million mints = ";
    	cout << million * mint << endl;
    	// cin.get();
    	return 0;
    }

执行结果：

tub = 3.333333, a million tubs = 3333333.250000,
    and ten million tubs = 33333332.000000
    mint = 3.333333 and a million mints = 3333333.333333

## fltadd.cpp ##

// fltadd.cpp -- precision problems with float
    #include <iostream>
    int main()
    {
    	using namespace std;
    	float a = 2.34E+22f;
    	float b = a + 1.0f;
    
    	cout << "a = " << a << endl;
    	cout << "b - a = " << b - a << endl;
    	// cin.get();
    	return 0;
    }

执行结果：

a = 2.34e+22
    b - a = 0

## arith.cpp ##

// arith.cpp -- some C++ arithmetic
    #include <iostream>
    int main()
    {
    	using namespace std;
    	float hats, heads;
    
    	cout.setf(ios_base::fixed, ios_base::floatfield); // fixed-point
    	cout << "Enter a number: ";
    	cin >> hats;
    	cout << "Enter another number: ";
    	cin >> heads;
    
    	cout << "hats = " << hats << "; heads = " << heads << endl;
    	cout << "hats + heads = " << hats + heads << endl;
    	cout << "hats - heads = " << hats - heads << endl;
    	cout << "hats * heads = " << hats * heads << endl;
    	cout << "hats / heads = " << hats / heads << endl;
    	// cin.get();
    	// cin.get();
    	return 0;
    }

执行结果：

Enter a number: 50.25
    Enter another number: 11.17
    hats = 50.250000; heads = 11.170000
    hats + heads = 61.419998
    hats - heads = 39.080002
    hats * heads = 561.292480
    hats / heads = 4.498657

## divide.cpp ##

// divide.cpp -- integer and floating-point division
    #include <iostream>
    int main()
    {
    	using namespace std;
    	cout.setf(ios_base::fixed, ios_base::floatfield);
    	cout << "Integer division: 9/5 = " << 9 / 5 << endl;
    	cout << "Floating-point division: 9.0/5.0 = ";
    	cout << 9.0 / 5.0 << endl;
    	cout << "Mixed division: 9.0/5 = " << 9.0 / 5 << endl;
    	cout << "double constants: 1e7/9.0 = ";
    	cout << 1.e7 / 9.0 << endl;
    	cout << "float constants: 1e7f/9.0f = ";
    	cout << 1.e7f / 9.0f << endl;
    	// cin.get();
    	return 0;
    }

执行结果：

Integer division: 9/5 = 1
    Floating-point division: 9.0/5.0 = 1.800000
    Mixed division: 9.0/5 = 1.800000
    double constants: 1e7/9.0 = 1111111.111111
    float constants: 1e7f/9.0f = 1111111.125000

## modulus.cpp ##

// modulus.cpp -- uses % operator to convert lbs to stone
    #include <iostream>
    int main()
    {
        using namespace std;
        const int Lbs_per_stn = 14;
        int lbs;
    
        cout << "Enter your weight in pounds: ";
        cin >> lbs;
        int stone = lbs / Lbs_per_stn;      // whole stone
        int pounds = lbs % Lbs_per_stn;     // remainder in pounds
        cout << lbs << " pounds are " << stone
             << " stone, " << pounds << " pound(s).\n";
        // cin.get();
        // cin.get();
        return 0; 
    }

执行结果：

Enter your weight in pounds: 181
    181 pounds are 12 stone, 13 pound(s).

## assign.cpp ##

// assign.cpp -- type changes on assignment
    #include <iostream>
    int main()
    {
        using namespace std;
        cout.setf(ios_base::fixed, ios_base::floatfield);
        float tree = 3;     // int converted to float
        int guess = 3.9832; // float converted to int
        int debt = 7.2E12;  // result not defined in C++
        cout << "tree = " << tree << endl;
        cout << "guess = " << guess << endl;
        cout << "debt = " << debt << endl;
        // cin.get();
        return 0;
    }

执行结果：

Enter your weight in pounds: 181
    181 pounds are 12 stone, 13 pound(s).

## typecast.cpp ##

// typecast.cpp -- forcing type changes
    #include <iostream>
    int main()
    {
    	using namespace std;
    	int auks, bats, coots;
    
    	// the following statement adds the values as double,
    	// then converts the result to int
    	auks = 19.99 + 11.99;
    
    	// these statements add values as int
    	bats = (int) 19.99 + (int) 11.99;   // old C syntax
    	coots = int(19.99) + int(11.99);  // new C++ syntax
    	cout << "auks = " << auks << ", bats = " << bats;
    	cout << ", coots = " << coots << endl;
    
    	char ch = 'Z';
    	cout << "The code for " << ch << " is ";    // print as char
    	cout << int(ch) << endl;                    // print as int
    	cout << "Yes, the code is ";
    	cout << static_cast<int>(ch) << endl;       // using static_cast
       // cin.get();
    	return 0;
    }

执行结果：

auks = 31, bats = 30, coots = 30
    The code for Z is 90
    Yes, the code is 90

## 二、复习题 ##

1.为什么c++有多种整形？

有多种整形类型，可以根据特定需求选择最合适的类型。例如，可以使用short来存储空格，使用long来确保存储容量，也可以寻找可提高特定计算的速度的类型。

2.声明与下述描述相符的变量。

a.short整数，值为80  
b.unsigned int整数，值为42110  
c.值为3000000000的整数

short a=80;       //or short int a=80;
    unsigned int b=42110;    //or unsigned b=42110;
    unsigned long long c=3000000000;    //or unsigned long c=3000000000;
    //(注意：不要指望int变量能够存储300000000)

3.c++提供了什么措施来防止超出整形的范围？

c++没有提供自动防止超出整型限制的功能，可以使用头文件climits来确定限制情况。

4.33L与33之间有什么区别？

常量33L的类型为long，常量33类型为int。

5.下面两条c++语句是否等价？

`char grade =45;`  
`char grade = 'A';`  
这两条语句并不真正等价，虽然对于某些系统来说，他们是等效的。最重要的是，只有在使用ASCII码的系统上，第一条语句才将得分设置为字母A，而第二条语句还可用于使用其他编码的系统。其次，65是一个int常量，而‘A’是一个char常量。

6.如何使用c++来找出编码88表示的字符？指出至少两种方法。

//method 1
    char c=88;
    cout<<c<<endl;
    //method 2
    cout.put(char(88));
    //method 3
    cout<<char(88)<<endl; //new-style type cast value to char
    cout<<(char)88<<endl; //old-style type cast value to char

7.将long赋值给float变量会导致舍入误差，将long值赋给double变量呢？将long long值赋给double变量呢？

这个问题取决于这两个类型的长度。如果long为4个字节，则没有损失。因为最大的long值是20亿，及有10位数。由于double提供至少13位有效数字，因而不需要进行任何舍入。long long类型可提供19位有效数字，超过了double保证的13位有效数字。

8.下列c++表达式的结果分别是多少？

a.8*9+2 b.6*3/4  
c.3/4*6 d.6.0*3/4  
e.15%4

a=74;b=4;c=0;d=4.5;e=3

9.假设x1和x2是两个double变量，你要将他们作为整数相加，再将结果赋给一个整型变量。请编写一条完成这项任务的c++语句。如果要将他们作为double值相加并转换为int呢？

int a=(int)x1+(int)x2;
    int a=int(x1)+int(x2);

要将他们作为double类型相加，在进行转换，可采取下述方式之一：

int a=(int)(x1+x2);
    int a=int(x1+x2);

10.下面每一条语句的变量都是什么类型？

a.`auto cars=15;`  
b.`auto iou=150.37f;`  
c.`auto level='B';`  
d.`auto crat=U'/U00002155';`  
e.`auto fract=8.25f/2.5;`

a. int  
b. float  
c. char  
d. char32\_t  
e. double

## 三、编程练习 ##

1.编写一个小程序，要求用户使用一个整数指出自己的身高（单位为英寸），然后将身高转换为英尺，该程序使用下划线字符来指示输入位置。另外，使用一个const符号来表示转换因子。

#include <iostream>
    
    const double Inch_per_feet = 12.0;
    using namespace std;
    int main(void)
    {
        cout << "Please enter your height:_____\b\b\b\b\b";
        double ht_inch;
        cin >> ht_inch;
    
        double ht_feet = ht_inch/Inch_per_feet;
        cout << "Your height is:" << ht_feet << " feets<<endl";    
    
        return 0;
    }

2.编写一个程序，要求以几英尺几英寸的方式输入其身高，并以磅为单位输入其体重。（使用3个变量来存储这些信息。）该程序报告其BMI（Body Mass Index ,体重指数）。为了计算BMI，该程序以英寸的方式指出用户的身高（一英尺为十二英寸），并将以英寸为单位的身高身高转换为以米为单位的身高（1英寸=0.0254米）。然后，将以磅为单位的体重转换为千克为单位的体重（1千克=2.2磅）。最后，计算相应的BMI-体重（千克）除以身高（米）的平方。用符号常量表示各种转换因子。

#include <iostream>
    using namespace std;
    const double Inch_per_feet = 12.0;
    const double Meter_per_inch = 0.0254;
    const double Pound_per_kilogram = 2.2;
    int main()
    {
        cout << "Enter your height of feet:";
        double ht_feet;
        cin >> ht_feet;
    
        cout << "Enter your height of inch:";
        double ht_inch;
        cin >> ht_inch;
    
        double ht_meter = (ht_feet*Inch_per_feet + ht_inch)*Meter_per_inch;
    
        cout << "Enter your weight in pound: ";
        double wt_pound;
        cin >> wt_pound;
    
        double wt_kilogram = wt_pound / Pound_per_kilogram;
    
        double BMI = wt_kilogram / ht_meter/ht_meter;
        cout << "BMI:" << BMI << endl;
        system("pause");
        return 0;
    }

3.编写一个程序，要求用户以度分秒的方式输入一个纬度，然后以度为单位显示该纬度。1度为60分，1分等于60秒，请以符号常量的方式表示这些值。对于每个输入值，应使用一个独立的变量存储它。下面是该程序运行时的情况：

`Enter a latitude in degrees,minutes,and seconds:`  
`First,enter the degrees:37`  
`Next,enter the minutes of arc:51`  
`Finally,enter the seconds of arc:19`  
`37 degrees,51 minutes,19 seconds =37.8553 degrees`

#include <iostream>
    using namespace std;
    const double Minute_per_degree = 60.0;
    const double Second_per_minute = 60.0;
    int main()
    {
        cout << "Enter a latitude in degrees,minutes,and seconds:"<<endl;
        cout << "First,enter the degrees:";
        int degrees;
        cin >> degrees;
    
        cout << "Next,enter the minutes of arc:";
        int minutes;
        cin >> minutes;
    
        cout << "Finally,enter the seconds of arc:";
        int seconds;
        cin >> seconds;
    
        double Degree = degrees + minutes / Minute_per_degree + seconds / Second_per_minute / Minute_per_degree;
    
        cout << degrees << " degrees, " << minutes << " minutes, " << seconds << " seconds = " << Degree<< " degrees";
        system("pause");
        return 0;
    }

4.编写一个程序，要求用户以整数方式输入秒数（使用long或long long变量存储），然后以天、小时、分钟和秒的方式显示这段时间。使用符号常量来表示每天有多少小时、每小时有多少分钟以及每分钟有多少秒。该程序的输出应与下面类似：

`Enter the number of seconds:3160000`  
`3160000 seconds = 365 days,17 hours,46 minutes,40 seconds`

#include <iostream>
    using namespace std;
    const int Sec_per_min = 60;
    const int Min_per_hour = 60;
    const int Hour_per_day = 24;
    int main()
    {
        cout << "Enter the number of seconds:";
        long long total_sec;
        cin >> total_sec;
    
        int sec = total_sec%Sec_per_min;
        int total_min = total_sec / Sec_per_min;
    
        int min = total_min%Min_per_hour;
        int total_hour = total_min / Min_per_hour;
    
        int hour= total_hour%Hour_per_day;
        int day = total_hour / Hour_per_day;
    
        cout << total_sec << " seconds = " << day << " days," << hour << " hours," << min << " minutes," << sec << " seconds";
    
        system("pause");
        return 0;
    }

5.编写一个程序，要求用户输入全球当前的人口和美国当前的人口（或其他国家的人口）。将这些信息存储在long long变量中，并让程序显示美国（或其他国家）的人口占全球人口的百分比。该程序的输出与下面类似：

`Enter the world's population:6898758899`  
`Enter the population of the US:310783781`  
`The population of the US is 4.50492% of the world population.`

#include <iostream>
    using namespace std;
    const int Sec_per_min = 60;
    const int Min_per_hour = 60;
    const int Hour_per_day = 24;
    int main()
    {
        cout << "Enter the world's population:";
        long long tW_population;
        cin >> tW_population;
    
        cout << "Enter the population of the US:";
        long long US_population;
        cin >> US_population;
    
        cout << "The population of the Us is " << double(US_population) / double(tW_population) *100<< "% of the world population";
    
        system("pause");
        return 0;
    }

6.编写一个程序，要求用户输入驱车里程（英里）和使用汽油量（加仑），然后指出汽车耗油量为一加仑的里程。如果愿意，也可以让程序要求用户以公里为单位输入距离，并以升为单位输入汽油量，然后指出欧洲风格的结果-即每100公里的耗油量（升）。

#include <iostream>
    using namespace std;
    int main()
    {
        cout << "Please enter the distance(miles):";
        double distance;
        cin >> distance;
    
        cout << "Please enter volume of gasoline(gallon):";
        double volume;
        cin >> volume;
    
        cout << "You can run " << distance / volume << " miles per gallon" << endl;
        system("pause");
        return 0;
    }

7.编写一个程序，要求每个用户按欧洲风格输入汽车的耗油量（每100公里消耗汽油量（升 ）），然后将其转换为美国风格的耗油量-每加仑多少英里。注意，除了使用不同的单位计量外，美国方法（距离/燃料）与欧洲方法（燃料/距离）相反。100公里等于62.14英里，1加仑等于3.875升。因此，19mpg大约合12.41/100km,127mpg大约合8.71/100km。

#include <iostream>
    using namespace std;
    int main()
    {
        cout << "Please enter fuel consumption per 100 km(UN):";
        double UN;
        cin >> UN;
    
        cout <<" Gallons per mile(US) : "<< 1 / UN*62.14*3.875;
    
        system("pause");
        return 0;
    }