ex9_2.cpp

纯粹是学习专用～

#include<iostream.h>

void main(){
	double fnum=31.415926535;
	cout<<"缺省域宽为:"<<cout.width()<<"位"<<'\n'; 
	cout<<"缺省精度为:"<<cout.precision()<<"位"<<'\n';//floatfield为0x1800
	cout<<"缺省表达方式:"<<fnum<<'\n'; //按值大小,自动决定定点还是科学数方式
	cout.setf(ios::scientific,ios::floatfield);//floatfield为0x1800
	cout<<"科学数表达方式:"<<fnum<<'\n';
	cout.setf(ios::fixed,ios::floatfield); //设为定点,取消科学数方式
	cout<<"定点表达方式:"<<fnum<<'\n';
	cout.precision(9); //精度为9位，小数点后9位
	cout.setf(ios::scientific,ios::floatfield); 
	cout<<"定点9位科学数表达方式"<<fnum<<'\n';
}