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C++学习--第一阶段

2021-02-06 17:57:35 作者：互联网

C++学习第一阶段小结

基本知识点
一些有趣但比较容易劝退的问题
小总结

基本知识点

1. C++代码的基本格式

#include <iostream>
using namespace std;

int main()
{
	// Code
	system("pause");
	return 0;
}

2. 数据类型：int、float、double、string（注意string要搭配头文件使用#include <string>）等

3. 选择结构

//if...else
if( condition )
{
	statements
}
else
{
	statements
}

//switch...case
switch( expression )
{
	case constant: statements
		break;
	default: //Code
		break;
		
//如果case里面要写多行代码可以
//case 1 :
//{
//	//Code
//}
//break;
//不然会报错

}

4. 循环结构

//while
while( condition )
{
	statements
}

//do...while
//注意do...while循环会先执行一次再判断条件
do
{
	statements
}while( condition );

//for
for ( initialization; condition; increment )
{
	statements
}

5. 数组

int a[3] = {a, b, c};
int a[] = {a, b, c};
int a[3];

6. 结构体

// 个人信息的结构体
struct person
{
	//注意使用string要包含头文件
    string name;
    int age;
    string sex;
}; //注意结尾的分号

7. 指针

int a = 10;
int * p;

p = &a; //指针指向变量a的地址
cout << *p << endl; //打印数据a的地址
cout << p << endl; //打印指针变量p

//通过*操作指针变量所指向的内存

8. 函数

#include <iostream>

void print()
{
	cout << "Hello World" << endl;
}

int main()
{
	print();	
	system("pause");
	return 0;
}

一些有趣但比较容易劝退的问题

1. 关于a++和++a的问题

int main()
{
    int a = 0;
    cout << a++ << endl;
    
//    cout << ++a << endl;

    system("pause")
    
    return 0;
}

2. const修饰指针

int main()
{
	int a = 10;
	int b = 10;

	const int * p1 = &a;
	p1 = &a;   //正确
	//*p = 100;//错误

	int * const p2 = &a;
	//p1 = &a; //错误
	*p = 100;  //正确

	const int * const p3 = &a;
	//p1 = &a; //错误
	//*p = 100;//错误

	//  const修饰什么，什么就不能修改
	
	system("pause");
	
	return 0;
}

3. 值传递与地址传递

void swap1(int a, int b)
{
	int temp = a;
	a = b;
	b = temp;	
}

void swap2(int * p1, int * p2)
{
	int temp = *p1;
	*p1 = *p2;
	*p2 = temp;	
}

int main()
{
	int a = 10;
	int b = 10;

	swap1(a, b);  //值传递不会改变实参
	cout << "a = " << a << endl;
	cout << "b = " << b << endl;

	swap2(&a, &b);  //地址传递会改变实参
	cout << "a = " << a << endl;
	cout << "b = " << b << endl;

	system("pause");

	return 0;
}

4. 冒泡排序

void bubbleSort(int a[])
{
    for (int i = 0; i < 5-1; i++) 
    {
        for (int j = 0; j < 5-i-1; j++) 
        {
            if (a[j]>a[j+1]) 
            {
                int temp = a[j];
                a[j] = a[j+1];
                a[j+1] = temp;
            }
        }
    }
}

int main()
{
    int a[5] = {1, 3, 5, 4, 2};
    
    bubbleSort(a);
    
    for (int i=0; i<5; i++)
    {
        cout << a[i] << "\t";
    }
    
    system("pause");
    
    return 0;
}

小总结

利用所学做一个通讯录系统

#include <iostream>
#include <string>
using namespace std;
#define MAX 1000

//联系人个人信息结构体
struct Person
{
    string name;
    int sex;
    int age;
    string phone;
    string address;
};

//通讯录结构体
struct Linkmen
{
    Person Array[MAX];
    int arrNum;
};

//添加联系人
void addLink(Linkmen * p)
{
    
    if (p->arrNum == MAX)
    {
        cout << "通讯录已满" << endl;
        return;
    }
    
    else
    {
        cout << "请输入姓名" << endl;
        string name;
        cin >> name;
        p->Array[p->arrNum].name = name;
        
        
        cout << "请输入性别" << endl;
        cout << "1----男" << endl;
        cout << "2----女" << endl;
        int sex;
        
        while (true)
        {
            cin >> sex;
            
            if(sex == 1 || sex == 2)
            {
                p->Array[p->arrNum].sex = sex;
                break;
            }
            cout << "输入有误，重新输入" << endl;
        }
        
        cout << "请输入年龄" << endl;
        int age;
        cin >> age;
        p->Array[p->arrNum].age = age;
        
        cout << "phone number?" << endl;
        string phone;
        cin >> phone;
        p->Array[p->arrNum].phone = phone;
        
        cout << "address?" << endl;
        string addr;
        cin >> addr;
        p->Array[p->arrNum].address = addr;
        
        p->arrNum++;
        cout << "添加成功" << endl;
        
    }
}

//显示全部联系人
void printLink(Linkmen * p)
{
    if (p->arrNum == 0)
    {
        cout << "记录为零，请添加联系人" << endl;
    }
    
    for (int i = 0; i < p->arrNum; i++)
    {
        cout << "姓名：  " << p->Array[i].name  << "\t";
        cout << "性别：  " << ( p->Array[i].sex == 1?"男":"女" ) << "\t";
        cout << "年龄：  " << p->Array[i].age << "\t";
        cout << "电话：  " << p->Array[i].phone << "\t";
        cout << "住址：  " << p->Array[i].address << endl;
    }
}

//删除联系人
void deleteLink(Linkmen * p, string name)
{
    if (p->arrNum == 0)
    {
        cout << "记录为零，请添加联系人" << endl;
    }
    
    for (int i = 0; i < p->arrNum; i++)
    {
        if(name == p->Array[i].name)
        {
            p->Array[i] = p->Array[i+1];
            p->arrNum--;
            cout << "删除成功" << endl;
            return;
        }
    }
    cout << "联系人不存在,请重新输入" << endl;
}

//查找联系人
void searchLink(Linkmen * p, string name)
{
    if (p->arrNum == 0)
    {
        cout << "记录为零，请添加联系人" << endl;
    }
    
    for (int i = 0; i < p->arrNum; i++)
    {
        if(name == p->Array[i].name)
        {
            cout << "姓名：  " << p->Array[i].name  << "\t";
            cout << "性别：  " << ( p->Array[i].sex == 1?"男":"女" ) << "\t";
            cout << "年龄：  " << p->Array[i].age << "\t";
            cout << "电话：  " << p->Array[i].phone << "\t";
            cout << "住址：  " << p->Array[i].address << endl;
            return;
        }
    }
    cout << "联系人不存在,请重新输入" << endl;
}

//修改联系人
void alterLink(Linkmen * p, string name)
{
    if (p->arrNum == 0)
    {
        cout << "记录为零，请添加联系人" << endl;
    }
    
    for (int i = 0; i < p->arrNum; i++)
    {
        if(name == p->Array[i].name)
        {
            cout << "请输入姓名" << endl;
            string name;
            cin >> name;
            p->Array[i].name = name;
            
            
            cout << "请输入性别" << endl;
            cout << "1----男" << endl;
            cout << "2----女" << endl;
            int sex;
            
            while (true)
            {
                cin >> sex;
                
                if(sex == 1 || sex == 2)
                {
                    p->Array[i].sex = sex;
                    break;
                }
                cout << "输入有误，重新输入" << endl;
            }
            
            cout << "请输入年龄" << endl;
            int age;
            cin >> age;
            p->Array[i].age = age;
            
            cout << "phone number?" << endl;
            string phone;
            cin >> phone;
            p->Array[i].phone = phone;
            
            cout << "address?" << endl;
            string addr;
            cin >> addr;
            p->Array[i].address = addr;
            
            cout << "修改成功" << endl;
            
            return;
        }
    }
    cout << "联系人不存在,请重新输入" << endl;
}

//清空通讯录
void clearLink(Linkmen * p)
{
    for (int i = p->arrNum; i >= 0; i--)
    {
        p->Array[i] = p->Array[i+1];
    }
    p->arrNum=0;
    cout << "清空成功" << endl;
}

//展示菜单
void ShowMenu()
{
    cout << "************************" << endl;
    cout << "*****  1,添加联系人  *****" << endl;
    cout << "*****  2,显示联系人  *****" << endl;
    cout << "*****  3,删除联系人  *****" << endl;
    cout << "*****  4,查找联系人  *****" << endl;
    cout << "*****  5,修改联系人  *****" << endl;
    cout << "*****  6,清空联系人  *****" << endl;
    cout << "*****  0,退出通讯录  *****" << endl;
    cout << "************************" << endl;
}

int main()
{
    
    Linkmen a;
    a.arrNum = 0;
    
    int select;
    string name;
    
    while (true)
    {
        ShowMenu();
        
        cin >> select;
        
        switch (select)
        {
            case 1:
                addLink(&a);
                break;
            case 2:
                printLink(&a);
                break;
            case 3:
                cout << "输入想要删除的联系人" << endl;
                cin >> name;
                deleteLink(&a, name);
                break;
            case 4:
                cout << "输入想要查找的联系人" << endl;
                cin >> name;
                searchLink(&a, name);
                break;
            case 5:
                cout << "输入想要修改的联系人" << endl;
                cin >> name;
                alterLink(&a, name);
                break;
            case 6:
                clearLink(&a);
                break;
            case 0:
                cout << "欢迎下次使用" << endl;
                return 0;
                break;
            default:
                cout << "输入错误,请重新输入" << endl;
                break;
        }
    }
    return 0;
}

运行结果：

~~第一阶段结束，~~
搞起搞起，从入门到入土

标签：cout,--,C++,name,int,Array,sex,arrNum,第一阶段
来源： https://blog.csdn.net/JasoBiu/article/details/113728676

C++学习--第一阶段

C++学习 第一阶段小结

基本知识点

一些有趣但比较容易劝退的问题

小总结

C++学习第一阶段小结