C++基础语法学习1

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我是靠谱客的博主平常早晨，最近开发中收集的这篇文章主要介绍C++基础语法学习1，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

1，变量类型(常用)
C++中有
a,字符型char占1字节。
b,整型 short(2),int(4),long(linux系统中为4，windows中为8)，long long(8);
c，浮点型 float(4),double(8)。且他们在输出时默认为6为有效数字
d,布尔型 bool(1),只有两个值true ,false;

#include<iostream>

using namespace std;

int main()
{
        bool flag;

        flag = true;

        cout<<"flag="<<flag<<endl;

        flag = false;
        cout<<"flag="<<flag<<endl;


        return 0;
}

e,字符串型 string(需要包含#include头文件)；char str[] = “”;注意在C语言中可以这样写char *str = “hello c”;
在C++中不能这样使用会报警告

#include<iostream>
#include<string>

using namespace std;

int main()
{
        char str[] = "hello C++";
        cout<<str<<endl;

        string str1 = "hello C++";
        cout<<str1<<endl;

        char *str2 = "hello C++";//C++ forbid to doing this opeartion;

        cout<<str2<<endl;





        return 0;
}

2，C++中输出和输入与c语言最大的区别就是不需要占位符
cout<<" "<<str<<endl;
" "里面的东西原样输出，str为变量；

#include<iostream>
#include<string>
using namespace std;

int main()
{
        int zx=0;
        char zf = 'a';
        float fd = 3.1415;
        bool flag = false;
        string str = "hello";
        cout<<"please input zx"<<endl;
        cin>>zx;
        cout<<"zx="<<zx<<endl;

        cout<<"please input zf"<<endl;
        cin>>zf;
        cout<<"zf="<<zf<<endl;

        cout<<"please input fd"<<endl;
        cin>>fd;
        cout<<"fd="<<fd<<endl;

        cout<<"please input flag"<<endl;
        cin>>flag;
        cout<<"flag="<<flag<<endl;

        cout<<"please input str"<<endl;
        cin>>str;
        cout<<"str="<<str<<endl;

        return 0;
}

3，运算符
在C++中的运算符都和C中一样。注意取模运算不能让两个小数取模。
4，条件结构，循环结构，顺序结构
条件结构：if()else()

#include<iostream>
using namespace std;

int main()
{
	while(1){
	int score=0;
	cout<<"please input score"<<endl;
	cin>>score;
	if(score>=600){
			if(score>=650){
					cout<<"perfect"<<endl;
					}
			else{
				cout<<"nice"<<endl;	
			
					}
			}
	else if(score>=500){
				cout<<"good"<<endl;
				}
	else{
	
		cout<<"bad"<<endl;
	
	}
}

	return 0;
}

循环结构do{}while();for(){}
顺序结构switch() {
case 0:
break;
default:
break
}
注意：switch条件只能是字符和数字
5，三目运算符

#include<iostream>

using namespace std;

int main()
{
	int a=0;
	int b = 20;
	int c = 30;
	cout<<"c="<<c<<endl;
	a>b?b:c = 100;
	cout<<"c = "<<c<<endl;
	a=a>b?b:c;
	cout<<"a = "<<a<<endl;
		

	return 0;
}

阶段小游戏猜数字

#include<iostream>
#include<ctime>

using namespace std;

int main()
{
	int vrand;
	int getkey;
	int count = 10;
	 srand((unsigned int)time(NULL));
	vrand = rand()%100+1;
	while(count){
		cout<<"please input your num"<<endl;
		cin>>getkey;
		if(getkey > vrand){
					cout<<"max"<<endl;
					}
		else if(getkey < vrand){
					cout<<"min"<<endl;
					}
		else if(getkey == vrand){
					cout<<"congradulation"<<endl;
					break;
						}
		count--;
	
	
	}


	return 0;
}

6，break;continue;goto
break:直接退出此次循环；
continue:不在执行continue这个循环以后的程序，直接进行下次循环；
goto:直接跳到标志位
7，冒泡排序
在这里插入图片描述

#include<iostream>

using namespace std;

int main()
{
	int array[]={5,8,9,4,6,3,7,1};
	
	int i = 0;
	int cnt = sizeof(array)/sizeof(int);
	int first=0;
	int count=cnt;
	 cout<<"correct"<<endl;
        for(int n=0;n<cnt;n++)
        {
                cout<<"array:"<<array[n]<<" ";

        }





	for(i=0;i<cnt;i++)
	{
	for(int j=0;j<cnt-i-1;j++)
	{
	  if(array[j]>array[j+1])
	  {
	       int temp =array[j];
	       array[j] = array[j+1];
	       	array[j+1]=temp;
	  		}
	}

	}
	cout<<"correct"<<endl;
	 cnt = sizeof(array)/sizeof(int);
	for(int n=0;n<cnt;n++)
	{
		cout<<"array:"<<array[n]<<" ";
	
	
	
	}

	return 0;
}``

8，二维数组
在这里插入图片描述

#include<iostream>
#include <stdio.h>

using namespace std;

int main()
{
        int array[3][3]={1,2,3,4,5,6,7,8,9};
        for(int i=0;i<3;i++)
        {
           for(int j=0;j<3;j++)
           {
                cout<<array[i][j];
           }
                putchar('n');
        }
        cout<<"array size= "<<sizeof(array)<<endl;
        cout<<"array one hang= "<<sizeof(array[0])<<endl;
        cout<<"array elemental size= "<<sizeof(array[0][0])<<endl;
        cout<<"what array  lie= "<<sizeof(array[0])/sizeof(array[0][0])<<endl;
        cout<<"what array  hang= "<<sizeof(array)/sizeof(array[0])<<endl;

        cout<<"array  address= "<<array<<endl;
        cout<<"array[0]  address= "<<array[0]<<endl;
        cout<<"array[1]  address= "<<array[1]<<endl;
        cout<<"array[2]  address= "<<array[2]<<endl;

        cout<<"array[0][0]  address= "<<&array[0][0]<<endl;
        cout<<"array[0][1]  address= "<<&array[0][1]<<endl;


        return 0;
}