C++ Primer plus学习总结（未完成）

2开始学习C++

2.1复习题

2.1.1 1C++的程序模块叫上面

函数

2.2.预处理编译指令的作用

#include

在最终编译之前，用iostream文件替换替换该编译指令

2.2编程题

2.2.5 将摄氏温度转换为华氏温度

#include
using namespace std;
double C2F(double C);
int main(){
  double C;
  cout<<"Please enter a Celsius value:";
  cin>>C;
  double F=C2F(C);
  cout<<C<<" degrees Celsius is "<<F<<" degrees Fahrenheit";
}


double C2F(double C){
    double F=1.8*C+32;
    return F    ;
}

2.2.7 输出特定格式的时间

#include
void format_time(int hours,int minutes)
{
    std::cout<<"Time: "<<hours<<":"<<minutes<<std::endl;
}
int main()
{
    int hours,minutes;
    std::cout<<"Enter the number of hours: ";
    std::cin >> hours;
    std::cout<<"Enter the number of minutes: ";
    std::cin >> minutes;

    format_time(hours,minutes);
    return 0;

}

std::cin>>val1>>val2; 可以输入多个数据。

#include

int main()
{
    int hours,minutes;
    std::cout<<"Enter the number of hours and minutes: \n";
    std::cin >> hours >> minutes;

    std::cout<<hours<<":"<<minutes<<std::endl;
    return 0;

}

总结

在 C++ 中，函数和变量一样都需要先定义后使用；

std::cout 可以输出多个变量，std::cin 可以输入多个变量；

C++ 的标准输入输出被定义在 iostream 中，需要先包含头文件才可以输入输出；

cin 和 cout 位于 std 命名空间下。

3 处理数据

3.1contenet

3.1.1 std::hex在cout中作用

#include
using namespace std;


int main(){
    int input_number;
    cout<<hex<<"the number input is  ";
    cin>>input_number;
    cout<<"output number is "<< input_number<<endl;
    return 0;
}

3.3编程题

3.3.5

#include
int main(){
    using namespace std;
    //cout.setf(ios_base::fixed,ios_base::floatfield)
    long long world_population ,us_population;
    cout<<"Enter the  world population:";
    cin>>world_population;
    cout<<"Enter the population of the US:";
    cin>>us_population;
    double rate=(double)us_population/world_population*100;
    cout<<"The population of the US is "<<rate<<"% of the world population.";
    return 0;

加以句

cout.setf(ios_base::fixed,ios_base::floatfield)

稳定小数点后6位

总结

强制类型转换的优先级为 2，高于乘除运算；使用 cin 读取数据产生错误，如果不进行特殊处理，则之后调用 cin 也无法正常读取缓冲区或触发用户输入；cin.clear() 可以清除错误。

4 符合类型

4.1content

4.1.1字符串长度超过定义

这里字符串长度要为定义的+1，即char[3]只能定义两个字符

#include
using namespace std;
int main(){
    char str[3]="ab";
    char str1[3]="abcdef";
    //char str[3]="a";
    cout<<str1<<endl;
    cout<<str<<endl;
    return 0 ;

}

若是超出字符，会提示出错，编译的化也会报错

若是短与定义会加入/0

#include
using namespace std;
int main(){
    char str[3]="ab";
    char str1[3]="a";
    //char str[3]="a";
    cout<<str<<endl;
    cout<<str1<<endl;
    return 0 ;

}

4.1.2给字符数组赋值

#include
#include
using namespace std;
int main(){
    char name[20],name1[20];
    strcpy(name,"ancsaca");
    strcpy(name1,name);
    cout<<"name value: "<<name<<endl;
     cout<<"name1 value: "<<name1<<endl;
    return 0;
    }

4.2复习题

4.2.1如何申明小列数据

char actor[30]
short betsie[100]
float chuck[13]
long double dipsea[64]

4.2.2使用模板类array而不是数组来完成问题1

array<char ,30> actor
array<short,100> betsie
array<float,13>chuck
array<long double ,64> dipsea

4.2.5编写一个语句来显示float数组ideas中第二个元素的值

cout<<ideas[1];
cout<<*(ideas+1)

4.2.8 设计一个结构

4.2.11假设ted是一个double变量，请声明一个指向ted的指针，并用该指针来显示ted的值

double* teddy=&ted;
cout<<*teddy;

4.2.14(int*)"hone sojdoa "s是否有效，如果有效打印出结果

4.2.15根据8的结构动态分配内存

4.2.17 vector and array

4.3编程练习

4.3.1 读取一行输入

#include
using namespace std;
int main(){
    const int len_name=15;
    char first_name[len_name];
    char last_name[len_name];
    char grade;
    int age;
    cout<<"what is your first name? ";
    cin.get(first_name,len_name).get();
    cout<<"what is your last name? ";
    cin>>last_name;
    cout<<"what letter grade do you deserve?";
    cin>>grade;
    cout<<"what is your age?";
    cin>>age;
    cout<<"Name: "<<last_name<<","<<first_name<<endl;
    cout<<"Grade: ";
    cout.put(grade+1);
    cout<<endl;
    cout<<"Age: "<<age<<endl;

}

4.3.2使用string类进行输入输出

#include
#include
int main()
{
  using namespace std;

  string name;
  string dessert;

  cout << "Enter your name\n";
  getline(cin,name);
  cout << "Enter your favorite dessert\n";
  getline(cin,dessert);
  cout <<"I have some delicious "<< dessert;
  cout << " for you, "<<name<<".\n";
  return 0;
}

4.3.6

4.3.10 new struct

#include
#include
using namespace std;
struct CandyBar
{
    string brand;
    double weight;
    int calory;
};
int main()
{
    CandyBar* snack=new CandyBar[3] {
            {"brand 1",11,111},
            {"brand 2",22,222},
            {"brand 3",33,333}
            };

    for(int i=0;i<3;i++)
    {
    cout<<"brand:"<<snack[i].brand<<endl;
    cout<<"weight:"<<snack[i].weight<<endl;
    cout<<"calorie:"<<snack[i].calory<<endl;
    }
    delete []snack;
    return 0;
}

4.8.4

总结

5循环和关系表达式

5.1 content

5.2复习题

5.2.1入口条件循环和出口用条件循环区别是上面？

参考 5.3do while

5.2.3 for循环

0369
12

5.2.5 do while

k=8

5.2.6

#include
using namespace std;
int main(){
int i=1
for(i;i<=64;i*=2)
	cout<<i<<endl
}

5.2.7如何在循环体中包括多条语句

5.2.8 int =（1,024）是否有效

5.11表达式和语句

5.3编程练习

5.3.1 习题一 求两个整数之间所有整数的和

#include
using namespace std;
int main(){
    int first,second;
    short sum=0;
    cin>>first>>second;
    cout <<endl;
    for (int i=first;i<=second;i++){
        sum+=i;

    }
    cout<<"the sum of number is "<<sum<<endl;
    return 0;
}

5.3.2 求阶乘 array

这里array的资料4.10.2

5.3.3

5.3.8 strcmp

参考内容5.1.14C语言风格字符比较

4.2.4getline 和get

#include
#include
using namespace std;
int main(){
    char word[10];
    int num=0;
    char ch;
    cout<<"Enter words (to stop ,type the word done) "<<endl;
    do{
    num++;
    cin>>word;
    cin.get(ch);   
    }while(strcmp(word,"done")!=0);
    cout<<" for sure"<<endl;
    cout<<"you entered a total of "<<num-1<<" words."<<endl;
    cout<<"ch is "<<ch<<endl;
    return 0;
   
}

5.3.9 在8的基础上用string

7函数

7.1content

7.5.1

#include
#include
using namespace std;
int main(){
    char ghost[15]="abcdefg";
    //char * str="abcdefg";
    const char * str="abcdefg";
    int n1 =strlen(ghost);
    int n2 =strlen(str);
    int n3=strlen("abcdefg");
    cout<<"n1=  "<<n1<<endl;
    cout<<"n2=  "<<n2<<endl;
    cout<<"n3=  "<<n3<<endl;
    return 0;
}

函数将字符串输入为char类型，这里之所以要用const char

等号两边的变量类型不一样，那么编译器会进行一种叫做 implicit conversion 的操作来使得变量可以被赋值。

在上面的表达式中等号右边的"abc"是一个不变常量，在c++中叫做string literal，type是const char *，而p则是一个char指针。如果强行赋值会发生什么呢？没错，就是将右边的常量强制类型转换成一个指针，结果就是我们在修改一个const常量。编译运行的结果会因编译器和操作系统共同决定，有的编译器会通过，有的会抛异常，就算过了也可能因为操作系统的敏感性而被杀掉。

7.2复习题

7.2.1函数使用的三个步骤

1定义函数
2提供原型
3调用函数

7.2.2定义函数

7.2.4 函数编写

void  set_array(int begin ,int end ,int value){
for(int *pt=begin;pt!=end;pt++)
	pt*=value;
}

7.2.6为什么不对类型为基础类型的函数使用const限定符

7.2.13

9内存模型和名称控件

9.1content

9.1.1定义赋值不会重复赋值

#include
using namespace std;
void count();
int main(){
    for(int j=0;j<10;j++)
        count();
        
        return 0;

    
}
void count(){
    static int i=0 ;//定义初始化
    //i=0;//赋值
    for(int a=0;a<10;a++)
        i+=a ;
        cout<<"out ="<<i<<endl;
}

如果直接的赋值会重新赋值变量

9.2复习题

9.2.1变量存储方式

9.2.2using申明和using编译指令

最小申明区域只有有局部变量不管在前在后都会被覆盖
具体内容再9-3中

#include
namespace  Jill{
    double fetch=2;
}
using namespace std;
int main(){
    double fetch=3;
    using namespace Jill;
    cout<<"fetch="<<fetch<<endl;
    cout<<"Jill_fetch= "<<Jill::fetch<<endl;
}

即使后使用using namespacee fetch依然是局部变量

9.2.3 不用using申明和编译指令

9.2.4 using申明

9.2.7

1
4，1，2
2
2
4，1，2
2

9.3 编程练习

9.3.1含有多文件的编译

9-1.cpp

// filename 9-1.cpp
#include
#include"golf.h"
const int Men=5;
int main()
{
    golf golfer[Men];
    int i;
    for( i=0;i<Men;i++)
    {
        if(setgolf(golfer[i])==0)
        break;
    }
    for( int j=0;j<i;j++)
    showgolf(golfer[j]);
    golf ann;
    setgolf(ann,"Ann Birdfree",24);
    showgolf(ann);
    handicap(ann,4);
    showgolf(ann);
    return 0;
}

golf.cpp

// filename golf.cpp
#include
#include
#include"golf.h"
using namespace std;
int setgolf(golf&g)
{
    cout<<"Enter the golfer's name:\n";
    cin.get(g.fullname,Len);
    if(g.fullname[0]=='\0')
    return 0;
    cout<<"Enter the handicap for "<<g.fullname<<endl;
    while(!(cin>>g.handicap))
    {
        cin.clear();
        while(cin.get()!='\n')
        continue;
        cout<<"Please enter an integer.\n";
    }
    cin.get();
    return 1;
}
void setgolf(golf&g,const char*name,int hc)
{
    strncpy(g.fullname,name,Len);
    g.handicap=hc;
}
void handicap(golf&g,int hc)
{
    g.handicap=hc;
}
void showgolf(const golf&g)
{
    cout<<"Golfer:"<<g.fullname<<"\n";
    cout<<"Handicap:"<<g.handicap<<"\n\n";
}

golf.h

// filename golf.h
const int Len=40;
struct golf
{
    char fullname[Len];
    int handicap;
};
void setgolf(golf&g,const char*name,int hc);
int setgolf(golf&g);
void handicap(golf&g,int hc);
void showgolf(const golf&g);

知识点

6.7中有知识点

#include
using namespace std;
int main(){
    cout<<"enter a number "<<endl;
    int num;
    for (int i=0;i<5;i++){
        while(!(cin>>num)){
            cin.clear();
            while(cin.get()!='\n')
                continue;
            cout<<i<<" times "<< "enter a number"<<endl;
        }
        cout<<i<<" number is "<<num<<endl;

    }
    return 0;
  
}

cin 要有一个回车结束，这里面如果出现非整数，会直接全部清空，到换行符’\n’
### 9.3.2 string 和char的区别
知识点在4-10

// static.cpp -- using a static local variable
#include 
// constants
const int ArSize = 10;

// function prototype
void strcount(const char * str);

int main()
{
    using namespace std;
    char input[ArSize];
    char next;

    cout << "Enter a line:\n";
    cin.get(input, ArSize);
    while (cin)
    {
        cin.get(next);
        while (next != '\n')    // string didn't fit!
            cin.get(next);      // dispose of remainder
        strcount(input);
        cout << "Enter next line (empty line to quit):\n";
        cin.get(input, ArSize);
    }
    cout << "Bye\n";
// code to keep window open for MSVC++
/*
cin.clear();
    while (cin.get() != '\n')
        continue;
    cin.get();
*/
    return 0;
}

void strcount(const char * str)
{
    using namespace std;
    static int total = 0;        // static local variable
    int count = 0;               // automatic local variable

    cout << "\"" << str <<"\" contains ";
    while (*str++)               // go to end of string
        count++;
    total += count;
    cout << count << " characters\n";
    cout << total << " characters total\n";
}

编码

#include
#include
using namespace std;
void strcount(const string str);
int main(){
    string input;
    cout << "Enter a line:\n";
    getline(cin,input);//4-10 知识点 
    while (input!="")
    {
        
        strcount(input);
        cout << "Enter next line (empty line to quit):\n";
         getline(cin,input);//4-10 知识点 
    }
    cout << "Bye\n";
// code to keep window open for MSVC++
/*
cin.clear();
    while (cin.get() != '\n')
        continue;
    cin.get();
*/
    return 0;

}
void strcount(const string str){
    static int total = 0;        // static local variable
    int count = 0; 
    cout << "\"" << str <<"\" contains ";
    while (str[count])               // go to end of string
        count++;
    total += count;
    cout << count << " characters\n";
    cout << total << " characters total\n";
}

9.2.4名称空间

中间永乐名称空间9.3还有三元表达式的内容

9-4.cpp

// filename 9-4.cpp
#include
#include"sales.h"
using namespace std;
int main()
{
    using namespace SALES;
    Sales salesBook;
    double salesList[]={12.2,11.16,10.61,16.24,11.53};
    setSales(salesBook,salesList,sizeof(salesList)/sizeof(salesList[0]));
    showSales(salesBook);
    Sales salesPen;
    setSales(salesPen);
    showSales(salesPen);
    return 0;
}

sales.h

namespace SALES
{
    const int QUARTERS=4;
    struct Sales
    {
        double sales[QUARTERS];
        double average;
        double max;
        double min;
    };
    //copiesthelesserof4ornitemsfromthearrayar
    //tothesalesmemberofsandcomputesandstoresthe
    //average,maximum,andminimumvaluesoftheentereditems;
    //remainingelementsofsales,ifany,setto0
    void setSales(Sales&s,const double ar[],int n);
    //gatherssalesfor4quartersinteractively,storesthem
    //inthesalesmemberofsandcomputesandstoresthe
    //average,maximum,andminimumvalues
    void setSales(Sales&s);
    //displayallinformationinstructures
    void showSales(const Sales&s);
}

sales.cpp

// filename sales.cpp
#include
#include"sales.h"
namespace SALES
{
    using std::cout;
    using std::cin;
    using std::endl;
    static double calaverage(double arr[],unsigned arrSize)
    {
        double sum=0;
        for( int i=0;i<arrSize;i++)
        sum+=arr[i];
        return sum/arrSize;
    }
    static double calmax(double arr[],unsigned arrSize)
    {
        double max=arr[0];
        for( int i=1;i<arrSize;i++)
        {
            if(max<arr[i])
            max=arr[i];
        }
        return max;
    }
    static double calmin(double arr[],unsigned arrSize)
    {
        double min=arr[0];
        for( int i=1;i<arrSize;i++)
        {
            if(min>arr[i])
            min=arr[i];
        }
        return min;
    }
    void setSales(Sales&s,const double ar[],int n)
    {
        unsigned times=n<QUARTERS?(unsigned)n:QUARTERS;
        for( int i=0;i<times;i++)
        s.sales[i]=ar[i];
        for( int i=times;i<QUARTERS;i++)
        s.sales[i]=0;
        s.average=calaverage(s.sales,times);
        s.max=calmax(s.sales,times);
        s.min=calmin(s.sales,times);
    }
    void setSales(Sales&s)
    {
        cout<<"Enter4sales:\n";
        for( int i=0;i<QUARTERS;i++)
        {
            cout<<"sales"<<i+1<<":";
            cin>>s.sales[i];
        }
        s.average=calaverage(s.sales,QUARTERS);
        s.max=calmax(s.sales,QUARTERS);
        s.min=calmin(s.sales,QUARTERS);
    }
    void showSales(const Sales&s)
    {
        cout<<"sales:";
        for( int i=0;i<QUARTERS;i++)
        cout<<s.sales[i]<<" ";
        cout<<endl;
        cout<<"average:"<<s.average<<endl;
        cout<<"max:"<<s.max<<endl;
        cout<<"min:"<<s.min<<endl;
    }
}

10对象和类

10.1 content

10.2复习题

10.2.1什么是类

类是现实中物体的抽象，类声明定义了数据如何储存，同时指定了用来访问和操作这些数据的方法。

10.2.2类是如何实现抽象、封装和数据隐藏的

10.2.5

10.2.6类的构造函数何时被调用？类析构函数呢？

10.2.10 this和 *this

this指针是类方向可以使用的指针，它指向类调用方法的对象。*this是对象本身

10.3 编程练习