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 <iostream>
#include <climits>//use limits.h for older systems 在老系统中用limits.h
int 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 <iostream>
#define ZERO 0//make ZERO symbol for 0 value 定义ZERO为0
#include <climits>//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 <iostream>
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 <iostream>
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;
}//chartype.cpp -- the char type#include "stdafx.h"
#include <iostream>
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 <iostream>
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 <iostream>
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 <iostream>
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 <iostream>
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 <iostream>
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 <iostream>
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 <iostream>
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 <iostream>
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 <iostream>
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<int>(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 <iostream>
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;
}