C++中类型数据所占字节数

int main()
{
	int a=5.4;

	cout<<"Hello World ! \n";
	cout<<"char size is:"<<sizeof(char)<<endl;
	cout<<"char* size is:"<<sizeof(char*)<<endl;
	cout<<"short-int size is:"<<sizeof(short int)<<endl;
	cout<<"int size is:"<<sizeof(int)<<endl;
    cout<<"unsigned-int size is:"<<sizeof(unsigned int)<<endl;
	cout<<"long size is:"<<sizeof(long)<<endl;

	cout<<"float size is:"<<sizeof(float)<<endl;
	cout<<"double size is:"<<sizeof(double)<<endl;
	cout<<"bool size is:"<<sizeof(bool)<<endl;
	//cout<<"a is:"<<a<<endl;
	return 0;

int，long int，short int的宽度都可能随编译器而异。但有几条铁定的原则（ANSI/ISO制订的）： 
1 sizeof(short int)<=sizeof(int) 
2 sizeof(int)<=sizeof(long int) 
3 short int至少应为16位（2字节） 
4 long int至少应为32位。