C++的数据类型你真的了解吗

#include<iostream>
using namespace std;
int main()
{
	//整型
	//1.短整型
	short num1 = 32768;
	//2.整型
	int num2 = 10;
	//3.长整型
	long num3 = 10;
	//4.长长整型
	long long num4 = 10;
	cout << "num1=" << num1 << endl;
	cout << "num2=" << num2 << endl;
	cout << "num3=" << num3 << endl;
	cout << "num4=" << num4 << endl;
	system("pause");
	return 0;
}

short num1 = 32768

sizeof{数据类型/变量}

#include<iostream>
using namespace std;
int main()
{
	//利用sizeof求出数据类型占用大小
	short num1 = 10;
	int num2 = 10;
	long num3 = 10;
	long long num4 = 10;
	cout << "short占用内存空间为：" << sizeof(short) << endl;
	cout << "num1占用内存空间为：" << sizeof(num1) << endl;
	cout << "int占用内存空间为：" << sizeof(int) << endl;
	cout << "num2占用内存空间为：" << sizeof(num2) << endl;
	cout << "long占用内存空间为：" << sizeof(long) << endl;
	cout << "num3占用内存空间为：" << sizeof(num3) << endl;
	cout << "long long占用内存空间为：" << sizeof(long long) << endl;
	cout << "num4占用内存空间为："      << sizeof(num4)      << endl;
	system("pause");
	return 0;
}

float f1 = 3.14f

#include<iostream>
using namespace std;
int main()
{	//默认情况下，输出一个小数，会显示最多6位有效数字
	//1.单精度
	float f1 = 3.1415926f;
	cout << "f1=" << f1 << endl;
	//2.双精度
	double d1 = 3.1415926;
	cout << "d1=" << d1 << endl;
	//占用内存查看
	cout << "float占用内存空间为：" << sizeof(float) << endl;
	cout << "double占用内存空间为：" << sizeof(double) << endl;
	//科学计数法
	float f2 = 3e2f;
	cout << "f2=" << f2 << endl;
	float f3 = 3e-2f;
	cout << "f3=" << f3 << endl;
	system("pause");
	return 0;
}

#include<iostream>
using namespace std;
int main()
{
	//字符型变量创建方式
	char ch = 'a';
	cout << ch << endl;
	//字符型变量所占内存大小
	cout << "char字符型变量所占内存:" << sizeof(char) << endl;
	//字符型变量常见错误
	// char ch2="b";
	// char ch2='abc';
	//字符型变量对应ASCII编码
	cout <<"字符A的ASCII码值为："<<(int)'A' << endl;
	cout << "变量ch的ASCII码值为：" << (int)ch << endl;
	system("pause");
	return 0;
}

#include<iostream>
using namespace std;
int main()
{	//换行符 \n
	cout << "hello world\n"<<endl;
	//反斜杠 \      
	cout << "\\" << endl;
	/*水平制表符 \t  
	使用空格补齐位置，使得所占位置为8的倍数
	输入正好为8个时，输出会多8个空格	*/
	cout << "aaaa\ttheworld" << endl;
	cout << "aaa\ttheworld" << endl;
	cout << "aaaaaaaa\ttheworld" << endl;
	cout << "aaaaaaaaa\ttheworld" << endl;
	cout << "aaaaaaaaaaa\ttheworld" << endl;
	
	system("pause");
	return 0;
}

#include<iostream>#include<string>using namespace std;int main(){//1.C风格字符串，注意加中括号[]char str[] = "hello world";cout << str << endl;//2.C++风格字符串,注意加头文件#include<string>string str2 = "hello world";cout << str2 << endl;system("pause");return 0;}#include<iostream>
#include<string>
using namespace std;
int main()
{	
	//1.C风格字符串，注意加中括号[]
	char str[] = "hello world";
	cout << str << endl;
	//2.C++风格字符串,注意加头文件#include<string>
	string str2 = "hello world";
	cout << str2 << endl;
	system("pause");
	return 0;
}

#include<iostream>#include<string>using namespace std;int main(){//1.创建bool数据类型bool flag = true;cout << flag << endl;flag = false;cout << flag << endl;//本质是1就是真，0就是假。//2.查看bool类型所占内存空间cout <<"bool类型所占内存空间为:" << sizeof(bool) << endl;system("pause");return 0;}#include<iostream>
#include<string>
using namespace std;
int main()
{
	//1.创建bool数据类型
	bool flag = true;
	cout << flag << endl;
	flag = false;
	cout << flag << endl;
	//本质是1就是真，0就是假。
	//2.查看bool类型所占内存空间
	cout <<"bool类型所占内存空间为:" << sizeof(bool) << endl;
	system("pause");
	return 0;
}

cin >> 变量

#include<iostream>
#include<string>
using namespace std;
int main()
{
	//1.整型
	int a = 0; //尽量初始化，如果不初始化在使用或者打印它时都会报错。
	cout << "请给整型变量a赋值：" << endl;
	cin >> a;
	cout << "整型变量a=" << a << endl;
	//2.浮点型
	float f = 0.f; 
	cout << "请给浮点型变量f赋值：" << endl;
	cin >> f;
	cout << "浮点型变量f=" << f << endl;
	//3.字符型
	char ch = ' ';
	cout << "请给字符型变量ch赋值：" << endl;
	cin >> ch;
	cout << "字符型变量f=" << ch << endl;
	//4.字符串型
	string str = "abc";
	cout << "请给字符串型变量str赋值：" << endl;
	cin >> str;
	cout << "字符串型变量str=" << str << endl;
	//5.布尔型,用数字表示真假，只要输入不是0，那么就是1
	bool flag = false;
	cout << "请给布尔型变量flag赋值：" << endl;
	cin >> flag;
	cout << "布尔型变量flag=" << flag << endl;
	system("pause");
	return 0;
}