在《算法竞赛入门经典》一书中
习题1-5 打折 （discount）
一件衣服95元，若消费满300元，可打八五折。输入购买衣服件数，输出需要支付的金额（单位：元），保留两位小数。
我编写的代码为
#include<iostream>#include<iomanip>using namespace std;
int main(void){
double s;
cin>>s;
if(s*95>=300){
cout<<setiosflags(ios::fixed)<<setprecision(2)<<s*95*0.85<<endl;
}
else{
cout<<setiosflags(ios::fixed)<<setprecision(2)<<s*95<<endl;
}
return 0;
}
于是将C++中如何显示不同格式的小数查了一下：
Floating point output can be changed with<< setiosflags( ios::fixed ) : never use scientific notation //绝对不使用科学记数法。<< setiosflags( ios::scientific ) : always use scientific notation //使用科学记数法。<< resetiosflags( ios::floatfield ) : restores default (use fixed or scientific notation based on the precision)//重置为缺省。<< (re)setiosflags( ios::showpoint ) : controls if the trailing zeros and decimal point will be output (default is no) //控制小数点后面的零是否显示。<< setprecision( digits ) : if fixed or scientific format is selected, controls the number of digits after the decimal place, otherwise controls the total number of significant digits// 如果fixed或者scientific已经确定了，则控制小数点后面的位数；否则，控制所有位数。
#include <iostream>#include <iomanip>using namespace std;
int main(void){
double S = 0.000000123;
double A = 456.7;
double B = 8910000000000.0;
cout << "default precision is " << cout.precision() << endl;
// 6 cout << " S = " << S << endl;
// 1.23e-07 cout << " A = " << A << endl;
// 456.7 cout << " B = " << B << endl;
// 8.91e+12 cout << setiosflags(ios::showpoint) << "ios::showpoint ON" << endl;
cout << " S = " << S << endl;
// 1.23000e-07 cout << " A = " << A << endl;
// 456.700 cout << " B = " << B << endl;
// 8.91000e+12 cout << resetiosflags(ios::showpoint) << "ios::showpoint OFF" << endl;
cout << setiosflags(ios::fixed) << "ios::fixed ON" << endl;
cout << " S = " << S << endl;
// 0.000000 cout << " A = " << A << endl;
// 456.700000 cout << " B = " << B << endl;
// 8910000000000.000000 cout << resetiosflags(ios::fixed) << setiosflags(ios::scientific) << "ios::scientific ON" << endl;
cout << " S = " << S << endl;
// 1.230000e-07 cout << " A = " << A << endl;
// 4.567000e+02 cout << " B = " << B << endl;
// 8.910000e+12}
输出为：
default precision is 6
S = 1.23e-007
A = 456.7
B = 8.91e+012
ios::showpoint ON
S = 1.23000e-007
A = 456.700
B = 8.91000e+012
ios::showpoint OFF
ios::fixed ON
S = 0.000000
A = 456.700000
B = 8910000000000.000000
ios::scientific ON
S = 1.230000e-007
A = 4.567000e+002
B = 8.910000e+012
--------------------------------
Process exited after 0.02482 seconds with return value 0
请按任意键继续. . .
以上这篇C++中小数点输出格式(实例代码)就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持脚本之家。
