C03-数据类型大分类

原题链接：49776.蒟蒻队笔记汇总

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2025-06-22 12:25:22

发布于：江苏

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一、课堂部分笔记

1.两种控制小数点的方式

#include<iostream>
#include<iomanip>

using namespace std;
int main(){
	double pi = 3.1415926;
	cout << fixed << setprecision(3) << pi << endl; //C++ 
	printf("%.3lf", pi); 	//C 
	
	return 0;
}

2.计算内存大小，单位是Byte

#include<iostream>
using namespace std;
int main(){
	cout << sizeof (int) << endl;
	cout << sizeof (long long) << endl;
	cout << sizeof (short) << endl;
	cout << sizeof (long) << endl;
	cout << sizeof (long double) << endl;

	return 0;
}

#if 0
1 B = 8 bit 
最小单位：bit（位） 二进制位 
常用单位： Byte（字节）
1 KB（千字节）= 1024 B 
1 MB（兆字节）= 1024 KB
1 GB（吉字节）= 1024 MB
1 TB
1 PB
1 EB

3.整数类型的占位符

#include<iostream>
using namespace std;
int main(){
	int a = 98, b = 86, c = 93;
	cout << "语文：" << a << endl;
	cout << "数学：" << b << endl;
	cout << "英语：" << c << endl;
	
	printf("语文：%d\n",a);//%d是int类型占位符 
	printf("数学：%d\n",b);
	printf("英语：%d\n",c);

	return 0;
}

4.交换两个数

#include<iostream>
using namespace std;
int main(){
	int a = 20, b = 22;
	int t = a;	//空杯子装a 
	a = b;		//将b放入空杯子a 
	b = t; 		//空杯子中的a放入b 
	printf("a=%d\nb=%d\n", a,  b); 

	return 0;
}