C++数据类型大小

最新推荐文章于 2025-05-30 09:14:39 发布

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最新推荐文章于 2025-05-30 09:14:39 发布

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文章标签： c/c++

本文介绍了C++中各种基本数据类型的字节大小，并通过示例代码展示了如何使用sizeof操作符来获取这些信息。此外，还讨论了不同数据类型的应用场景及注意事项。

#include <iostream>

using namespace std;

void main()

{

cout<<"size of bool: "<<sizeof(bool)<<" bytes"<<endl;

cout<<"size of char: "<<sizeof(char)<<" bytes"<<endl;

cout<<"size of unsigned char: "<<sizeof(unsigned char)<<" bytes"<<endl;

cout<<"size of wchar_t: "<<sizeof(wchar_t)<<" bytes"<<endl;

cout<<"size of short: "<<sizeof(short)<<" bytes"<<endl;

cout<<"size of int: "<<sizeof(int)<<" bytes"<<endl;

cout<<"size of unsigned int/unsigned: "<<sizeof(unsigned)<<" bytes"<<endl;

cout<<"size of size_t: "<<sizeof(size_t)<<" bytes"<<endl;

cout<<"size of long: "<<sizeof(long)<<" bytes"<<endl;

cout<<"size of unsigned long: "<<sizeof(unsigned long)<<" bytes"<<endl;

cout<<"size of float: "<<sizeof(float)<<" bytes"<<endl;

cout<<"size of double: "<<sizeof(double)<<" bytes"<<endl;

cout<<"size of long double: "<<sizeof(long double)<<" bytes"<<endl;

//out of boundrary testing

//warning C4305: '=' : truncation from 'const int' to 'unsigned char'

//warning C4309: '=' : truncation of constant value

unsigned char ch;

ch=333;

cout<<"Truncation from const int to unsigned char, 333 will become: "<<(int)ch<<endl;

}

输出结果：
size of bool: 1 bytes
size of char: 1 bytes
size of unsigned char: 1 bytes
size of wchar_t: 2 bytes
size of short: 2 bytes
size of int: 4 bytes
size of unsigned int/unsigned: 4 bytes
size of size_t: 4 bytes
size of long: 4 bytes
size of unsigned long: 4 bytes
size of float: 4 bytes
size of double: 8 bytes
size of long double: 8 bytes
Truncation from const int to unsigned char, 333 will become: 77

注解：
1. wchar_t类型用于扩展字符集，如汉字和日语，这些字符不能用单个char表示
2. 一般，short类型为半个机器字(word)长，int类型为一个机器字长，long类型为一个或两个机器字长
3. 在32位机中，int类型和long类型的字长通常是相同的
4. bool类型表示真值true和假值false，0值类型代表false，任何非0的值都代表true
5. 除bool类型外，整型可以是带符号的(signed)也可以是无符号的(unsigned)
6. int，short，long都默认为带符号型
7. 对于unsigned类型来说，编译器对取值求模，取所得值