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一，总结

C++的基本类型分为两组：一组由存储为整数的值组成，另一组由存储为浮点格式的值组成。整型之间通过存储值时使用的内存量及有无符号来区分。整型从最小到最大依次是：bool、char、signedchar、 unsignedchar、short、unsignedshort、int、unsignedint、long、unsignedlong以及 C++11新增的 longlong 和unsignedlonglong。还有一种wchar_t类型，它在这个序列中的位置取决于实现。C++11新增了类型 char16_t和char32_t,它们的宽度足以分别存储16和32位的字符编码。C++确保了char足够大，能够存储系统基本字符集中的任何成员，而wchar_t则可以存储系统扩展字符集中的任意成员，short至少为16 位，而int至少与short—样长,long至少为32位.且至少和int—样长。确切的长度取决于实现。

字符通过其数值编码来表示。1/0系统决定了编码是被解释为字符还是数字。

浮点类型可以表示小数值以及比整型能够表示的值大得多的值。3种浮点类型分别是float、double和 longdouble。C++确保float不比double长，而double不比longdouble长。通常，float使用32位内存，double使用64位，longdouble使用80到128位。

通过提供各种长度不同、有符号或无符号的类型，C++使程序员能够根据特定的数据要求选择合适的类型。

C++使用运算符来提供对数字类型的算术运算：加、减、乘、除和求模。当两个运算符对同一个操作数进行操作时，C++的优先级和结合性规则可以确定先执行哪种操作。

对变量赋值、在运算中使用不同类型，使用强制类型转换时，C++将把值从一种类型转换为另一种类型。很多类型转换都是“安全的”即可以在不损失和改变数据的情况下完成转换。例如，可以把int值转换为long值，而不会出现任何问题。对其他一些转换，如将浮点类型转换为整型，则需要更加小心。

开始，读者可能觉得大量的C++基本类型有些多余，尤其是考虑到各种转换规则时。但是很可能最终 .将发现，某些时候，只有一种类型是需要的,此时您将感谢C++提供了这种类型。

二，程序清单

程序清单3.1 整型长度

// limits.cpp -- some integer limits#include "stdafx.h"#include 
   
    #include 
    
     //use limits.h for older systems 在老系统中用limits.hint limits(){	using namespace std;	int n_int = INT_MAX;//initialize n_int to max int value 赋予int最大取值	short n_short = SHRT_MAX;//symbols defined in climits file 这些符号已经在climits文件中被定义了	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;	return 0;}
    
   

程序清单3.2 无符号类型

//exceed.cpp -- exceeding some integer limits#include "stdafx.h"#include 
   
    #define ZERO 0//make ZERO symbol for 0 value 定义ZERO为0#include 
    
     //defines INT_MAX as largest int value 定义int最大值int exceed(){	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;	return 0;}
    
   

程序清单3.3整型字面值

//hexoct.cpp -- show hex and octal literals#include "stdafx.h"#include 
   
    int hexoct(){	using namespace std;	int chest  = 42;  //decimal integer literal 10进制	int waist  = 0x42;//hexadecimal integer literal 16进制	int inseam = 042; //octal integer literal 8进制		cout << "Monsieur cut a striking figue!\n";	cout << "cheat  = " << chest <<  " {42 in decimal}\n";	cout << "waist  = " << waist <<  " {0x42 in hex}\n";	cout << "inseam = " << inseam << " {042 in octal}\n";	return 0;}
   

程序清单3.4整型字面值

//hexoct2.cpp -- display values in hex and octal#include "stdafx.h"#include 
   
    int hexoct2(){	using namespace std;	int chest  = 42;  	int waist  = 42;	int inseam = 42;	cout << "Monsieur cut a striking figue!\n";	cout << "cheat  = " << chest << " {decimal for 42}\n";	cout << hex;//manipulator for changing number base	cout << "waist  = " << waist << " {hexadecimal for 42}\n";	cout << oct;//manipulator for changing number base	cout << "inseam = " << inseam << " {octal for 42}\n";	return 0;}
   

程序清单3.5char型

//chartype.cpp -- the char type

#include "stdafx.h"#include 
   
    int chartype(){	using namespace std;	char ch;  //declare a char variable 声明字符变量	cout << "Enter a character: " << endl;	cin >> ch;	cout << "Hola: ";	cout << "Thank you for the " << ch << " character" << endl;	return 0;}
   

程序清单3.6char型

//morechar.cpp -- the char type and int type contrasted#include "stdafx.h"#include 
   
    int morechar(){	using namespace std;	char ch = 'M';	int  i  = ch;	cout << "The ASCII code for " << ch << " is " << i << endl;	cout << "Add one to the character code: " << endl;	ch = ch + 1;	i  = ch;	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);//可以用ASCII码表示字符	//using cout.put() to display a char constant	cout.put('!');//可以用('')直接显示字符	cout << endl << "Done" << endl;	return 0;}
   

程序清单3.7转义序列

//bondini.cpp -- using escape sequences#include "stdafx.h"#include 
   
    int bondini(){	using namespace std;	cout << "\aOpeartion \"HyperHype\" is now activated!\n";//‘\"’是双引号符	cout << "Enter your agent code:________\b\b\b\b\b\b\b\b";//‘\b’是退格符	long code;	cin >> code;	cout << "\aYou entered " << code << "...\n";	cout << "\aCode verified! Proceed with Plan Z3!\n";	return 0;}
   

程序清单3.8浮点类型

//floatnum.cpp -- floating-point type#include "stdafx.h"#include 
   
    int floatnum(){	using namespace std;	cout.setf(ios_base::fixed, ios_base::floatfield);//fixed-point定点表示法	float tub = 10.0 / 3.0;//good to about 6 place	double mint = 10.0 / 3.0;//good to about 15 place	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;	return 0;}
   

程序清单3.9浮点类型

//fltadd.cpp -- precision problems with float#include "stdafx.h"#include 
   
    int fltadd(){	using namespace std;	float a = 2.34E+22f;	float b = a + 1.0f;	cout << "a = " << a << endl;	cout << "b - a = " << b - a << endl;	return 0;}//2.34E+22小数点左边有23位数字，在第23上加上1，对于只能表示数字中的前6位或前7位的float类型，因此修改第23位对这个值不会有影响。
   

程序清单3.10算数运算符

//arith.cpp -- some C++ arithmetic#include "stdafx.h"#include 
   
    int arith(){	using namespace std;	float hats, heads;	cout.setf(ios_base::fixed, ios_base::floatfield);	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;	return 0;}
   

程序清单3.11除法分支

//divide.cpp -- integer and floating-point division#include "stdafx.h"#include 
   
    int divide(){	using namespace std;	cout.setf(ios_base::fixed, ios_base::floatfield);	cout << "Integer division: 9/5 = ";	cout << 9 / 5 << endl;	cout << "Floating-point division: 9.0/5.0 = ";	cout << 9.0 / 5.0 << endl;	cout << "Mixed division: 9.0/5 = ";	cout << 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;	return 0;}
   

程序清单3.12求模运算

//modulus.cpp -- uses % oprator to convert lbs to stone#include "stdafx.h"#include 
   
    int modulus(){	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;	int pounds = lbs % Lbs_per_stn;	cout << lbs << " pounds are " << stone << " stone, " << pounds << " pound(s).\n";	return 0;}
   

程序清单3.13变量初始化

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

程序清单3.14强制类型转换

//typecast.cpp -- forcing type changes#include "stdafx.h"#include 
   
    int typecast(){	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 强制整数相加	bats = (int) 19.99 + (int) 11.99; //old C syntax C语言句法	coots = int(19.99) + int(11.99); //new C++ syntax C++句法	cout << "auks = " << auks << ", bats = " << bats;	cout << ", coot = " << 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
    
     (ch) << endl;    //using static cast	return 0;}
    
   

课后编程练习答案

//practice.cpp -- answer of program practice#include "stdafx.h"#include 
   
    int main(){	using namespace std;		//problem 1	/*cout << "Enter your height(inch):___\b\b\b";	const int tran = 12;	int height;	int inch;	int feet;	cin >> height;	feet = height / tran;	inch = height % tran;	cout << " your height(feet) are " << feet << " feet " << inch << " inch.\n";*/		//problem 2	/*cout << "Enter your height(feet):";	int feet;	int inch;	double height;	cin >> feet;	cout << "Enter your height(inch):";	cin >> inch;	height = (feet * 12 + inch) * 0.0254;	cout << "Enter your weight:";	int weight;	cin >> weight;	double bmi;	bmi = weight / (height*height);	cout << "your BMI is: " << bmi << endl;*/		//problem 3	/*cout << "Enter a latitude in degrees, minutes, and second:\n";	const int dm = 60;	const int ds = 360;		int degree;	int minute;	int second;	double degrees;   	cout << "First, enter the degrees: ";        cin >> degree;	cout << "Second, enter the minutes: ";        cin >> minute;	cout << "Finally, enter the seconds:";        cin >> second; 	degrees = (double)degree+ (double)minute / dm + (double)second / ds;/* 	cout << degree << " dgrees, " << minute << " minutes, " << second << " seconds = " << degrees << " degrees\n";*/	//problem 4	/*cout << "Enter the number of seconds: ";	const int ds = 3600 * 24;	const int ms = 60;	const int hs = 3600;	int second;	cin >> second; 	int day;	int hour;	int minute;	int second1;	day = second / ds;	hour = (second - day * ds) / hs;	minute = (second - day * ds) % hs / ms;	second1 = (second - day * ds) % hs % ms;	cout << second << " seconds = " 		 << day << " days," 		 << hour << " hours," 		 << minute << " minutes,"		 << second1 << " seconds\n";*/	//problem 5	/*cout << "Enter the world's population:";	long long wo;	cin >> wo;	cout << "Enter the polulation of US: ";	long long us;	cin >> us;	double per;	per = (double)us / (double)wo * 100;	cout << "the population of the US is " << per << "% of the world polulation";*/	//problem 6	/*cout << "Enter the distance:";	long dis;	cin >> dis;	cout << "Enter the oil: ";	long oil;	cin >> oil;	double per;	per = (double)oil / (double)dis * 100;	cout << "the oil consumption is " << per << " L / km";*/	//problem 7	/*cout << "Enter the oil consumption: ";	double con;	cin >> con;	double mpg;	mpg = con / 12.14 * 19;	cout << "the mpg is: " << mpg << " mpg" << endl;*/	return 0; 	}
   

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