我想在C＃中将double值显示为分数，我该怎么做？
由于
答案 0 :(得分：5)
为C＃尝试此Fraction课程。
/*
* Author: Syed Mehroz Alam
* Email: smehrozalam@yahoo.com
* URL: Programming Home "http://www.geocities.com/smehrozalam/"
* Date: 6/15/2004
* Time: 10:54 AM
*
*/
using System;
namespace Mehroz
{
/// <summary>
/// Classes Contained:
/// Fraction
/// FractionException
/// </summary>
/// Class name: Fraction
/// Developed by: Syed Mehroz Alam
/// Email: smehrozalam@yahoo.com
/// URL: Programming Home "http://www.geocities.com/smehrozalam/"
/// Version: 2.0
///
/// What's new in version 2.0:
/// * Changed Numerator and Denominator from Int32(integer) to Int64(long) for increased range
/// * renamed ConvertToString() to (overloaded) ToString()
/// * added the capability of detecting/raising overflow exceptions
/// * Fixed the bug that very small numbers e.g. 0.00000001 could not be converted to fraction
/// * Other minor bugs fixed
///
/// What's new in version 2.1
/// * overloaded user-defined conversions to/from Fractions
///
///
/// Properties:
/// Numerator: Set/Get value for Numerator
/// Denominator: Set/Get value for Numerator
/// Value: Set an integer value for the fraction
///
/// Constructors:
/// no arguments: initializes fraction as 0/1
/// (Numerator, Denominator): initializes fraction with the given numerator and denominator values
/// (integer): initializes fraction with the given integer value
/// (long): initializes fraction with the given long value
/// (double): initializes fraction with the given double value
/// (string): initializes fraction with the given string value
/// the string can be an in the form of and integer, double or fraction.
/// e.g it can be like "123" or "123.321" or "123/456"
///
/// Public Methods (Description is given with respective methods' definitions)
/// (override) string ToString(Fraction)
/// Fraction ToFraction(string)
/// Fraction ToFraction(double)
/// double ToDouble(Fraction)
/// Fraction Duplicate()
/// Fraction Inverse(integer)
/// Fraction Inverse(Fraction)
/// ReduceFraction(Fraction)
/// Equals(object)
/// GetHashCode()
///
/// Private Methods (Description is given with respective methods' definitions)
/// Initialize(Numerator, Denominator)
/// Fraction Negate(Fraction)
/// Fraction Add(Fraction1, Fraction2)
///
/// Overloaded Operators (overloaded for Fractions, Integers and Doubles)
/// Unary: -
/// Binary: +,-,*,/
/// Relational and Logical Operators: ==,!=,<,>,<=,>=
///
/// Overloaded user-defined conversions
/// Implicit: From double/long/string to Fraction
/// Explicit: From Fraction to double/string
/// </summary>
public class Fraction
{
/// <summary>
/// Class attributes/members
/// </summary>
long m_iNumerator;
long m_iDenominator;
/// <summary>
/// Constructors
/// </summary>
public Fraction()
{
Initialize(0,1);
}
public Fraction(long iWholeNumber)
{
Initialize(iWholeNumber, 1);
}
public Fraction(double dDecimalValue)
{
Fraction temp=ToFraction(dDecimalValue);
Initialize(temp.Numerator, temp.Denominator);
}
public Fraction(string strValue)
{
Fraction temp=ToFraction(strValue);
Initialize(temp.Numerator, temp.Denominator);
}
public Fraction(long iNumerator, long iDenominator)
{
Initialize(iNumerator, iDenominator);
}
/// <summary>
/// Internal function for constructors
/// </summary>
private void Initialize(long iNumerator, long iDenominator)
{
Numerator=iNumerator;
Denominator=iDenominator;
ReduceFraction(this);
}
/// <summary>
/// Properites
/// </summary>
public long Denominator
{
get
{ return m_iDenominator; }
set
{
if (value!=0)
m_iDenominator=value;
else
throw new FractionException("Denominator cannot be assigned a ZERO Value");
}
}
public long Numerator
{
get
{ return m_iNumerator; }
set
{ m_iNumerator=value; }
}
public long Value
{
set
{ m_iNumerator=value;
m_iDenominator=1; }
}
/// <summary>
/// The function returns the current Fraction object as double
/// </summary>
public double ToDouble()
{
return ( (double)this.Numerator/this.Denominator );
}
/// <summary>
/// The function returns the current Fraction object as a string
/// </summary>
public override string ToString()
{
string str;
if ( this.Denominator==1 )
str=this.Numerator.ToString();
else
str=this.Numerator + "/" + this.Denominator;
return str;
}
/// <summary>
/// The function takes an string as an argument and returns its corresponding reduced fraction
/// the string can be an in the form of and integer, double or fraction.
/// e.g it can be like "123" or "123.321" or "123/456"
/// </summary>
public static Fraction ToFraction(string strValue)
{
int i;
for (i=0;i<strValue.Length;i++)
if (strValue[i]=='/')
break;
if (i==strValue.Length) // if string is not in the form of a fraction
// then it is double or integer
return ( Convert.ToDouble(strValue));
//return ( ToFraction( Convert.ToDouble(strValue) ) );
// else string is in the form of Numerator/Denominator
long iNumerator=Convert.ToInt64(strValue.Substring(0,i));
long iDenominator=Convert.ToInt64(strValue.Substring(i+1));
return new Fraction(iNumerator, iDenominator);
}
/// <summary>
/// The function takes a floating point number as an argument
/// and returns its corresponding reduced fraction
/// </summary>
public static Fraction ToFraction(double dValue)
{
try
{
checked
{
Fraction frac;
if (dValue%1==0) // if whole number
{
frac=new Fraction( (long) dValue );
}
else
{
double dTemp=dValue;
long iMultiple=1;
string strTemp=dValue.ToString();
while ( strTemp.IndexOf("E")>0 ) // if in the form like 12E-9
{
dTemp*=10;
iMultiple*=10;
strTemp=dTemp.ToString();
}
int i=0;
while ( strTemp[i]!='.' )
i++;
int iDigitsAfterDecimal=strTemp.Length-i-1;
while ( iDigitsAfterDecimal>0 )
{
dTemp*=10;
iMultiple*=10;
iDigitsAfterDecimal--;
}
frac=new Fraction( (int)Math.Round(dTemp) , iMultiple );
}
return frac;
}
}
catch(OverflowException)
{
throw new FractionException("Conversion not possible due to overflow");
}
catch(Exception)
{
throw new FractionException("Conversion not possible");
}
}
/// <summary>
/// The function replicates current Fraction object
/// </summary>
public Fraction Duplicate()
{
Fraction frac=new Fraction();
frac.Numerator=Numerator;
frac.Denominator=Denominator;
return frac;
}
/// <summary>
/// The function returns the inverse of a Fraction object
/// </summary>
public static Fraction Inverse(Fraction frac1)
{
if (frac1.Numerator==0)
throw new FractionException("Operation not possible (Denominator cannot be assigned a ZERO Value)");
long iNumerator=frac1.Denominator;
long iDenominator=frac1.Numerator;
return ( new Fraction(iNumerator, iDenominator));
}
/// <summary>
/// Operators for the Fraction object
/// includes -(unary), and binary opertors such as +,-,*,/
/// also includes relational and logical operators such as ==,!=,<,>,<=,>=
/// </summary>
public static Fraction operator -(Fraction frac1)
{ return ( Negate(frac1) ); }
public static Fraction operator +(Fraction frac1, Fraction frac2)
{ return ( Add(frac1 , frac2) ); }
public static Fraction operator +(int iNo, Fraction frac1)
{ return ( Add(frac1 , new Fraction(iNo) ) ); }
public static Fraction operator +(Fraction frac1, int iNo)
{ return ( Add(frac1 , new Fraction(iNo) ) ); }
public static Fraction operator +(double dbl, Fraction frac1)
{ return ( Add(frac1 , Fraction.ToFraction(dbl) ) ); }
public static Fraction operator +(Fraction frac1, double dbl)
{ return ( Add(frac1 , Fraction.ToFraction(dbl) ) ); }
public static Fraction operator -(Fraction frac1, Fraction frac2)
{ return ( Add(frac1 , -frac2) ); }
public static Fraction operator -(int iNo, Fraction frac1)
{ return ( Add(-frac1 , new Fraction(iNo) ) ); }
public static Fraction operator -(Fraction frac1, int iNo)
{ return ( Add(frac1 , -(new Fraction(iNo)) ) ); }
public static Fraction operator -(double dbl, Fraction frac1)
{ return ( Add(-frac1 , Fraction.ToFraction(dbl) ) ); }
public static Fraction operator -(Fraction frac1, double dbl)
{ return ( Add(frac1 , -Fraction.ToFraction(dbl) ) ); }
public static Fraction operator *(Fraction frac1, Fraction frac2)
{ return ( Multiply(frac1 , frac2) ); }
public static Fraction operator *(int iNo, Fraction frac1)
{ return ( Multiply(frac1 , new Fraction(iNo) ) ); }
public static Fraction operator *(Fraction frac1, int iNo)
{ return ( Multiply(frac1 , new Fraction(iNo) ) ); }
public static Fraction operator *(double dbl, Fraction frac1)
{ return ( Multiply(frac1 , Fraction.ToFraction(dbl) ) ); }
public static Fraction operator *(Fraction frac1, double dbl)
{ return ( Multiply(frac1 , Fraction.ToFraction(dbl) ) ); }
public static Fraction operator /(Fraction frac1, Fraction frac2)
{ return ( Multiply( frac1 , Inverse(frac2) ) ); }
public static Fraction operator /(int iNo, Fraction frac1)
{ return ( Multiply( Inverse(frac1) , new Fraction(iNo) ) ); }
public static Fraction operator /(Fraction frac1, int iNo)
{ return ( Multiply( frac1 , Inverse(new Fraction(iNo)) ) ); }
public static Fraction operator /(double dbl, Fraction frac1)
{ return ( Multiply( Inverse(frac1) , Fraction.ToFraction(dbl) ) ); }
public static Fraction operator /(Fraction frac1, double dbl)
{ return ( Multiply( frac1 , Fraction.Inverse( Fraction.ToFraction(dbl) ) ) ); }
public static bool operator ==(Fraction frac1, Fraction frac2)
{ return frac1.Equals(frac2); }
public static bool operator !=(Fraction frac1, Fraction frac2)
{ return ( !frac1.Equals(frac2) ); }
public static bool operator ==(Fraction frac1, int iNo)
{ return frac1.Equals( new Fraction(iNo)); }
public static bool operator !=(Fraction frac1, int iNo)
{ return ( !frac1.Equals( new Fraction(iNo)) ); }
public static bool operator ==(Fraction frac1, double dbl)
{ return frac1.Equals( new Fraction(dbl)); }
public static bool operator !=(Fraction frac1, double dbl)
{ return ( !frac1.Equals( new Fraction(dbl)) ); }
public static bool operator<(Fraction frac1, Fraction frac2)
{ return frac1.Numerator * frac2.Denominator < frac2.Numerator * frac1.Denominator; }
public static bool operator>(Fraction frac1, Fraction frac2)
{ return frac1.Numerator * frac2.Denominator > frac2.Numerator * frac1.Denominator; }
public static bool operator<=(Fraction frac1, Fraction frac2)
{ return frac1.Numerator * frac2.Denominator <= frac2.Numerator * frac1.Denominator; }
public static bool operator>=(Fraction frac1, Fraction frac2)
{ return frac1.Numerator * frac2.Denominator >= frac2.Numerator * frac1.Denominator; }
/// <summary>
/// overloaed user defined conversions: from numeric data types to Fractions
/// </summary>
public static implicit operator Fraction(long lNo)
{ return new Fraction(lNo); }
public static implicit operator Fraction(double dNo)
{ return new Fraction(dNo); }
public static implicit operator Fraction(string strNo)
{ return new Fraction(strNo); }
/// <summary>
/// overloaed user defined conversions: from fractions to double and string
/// </summary>
public static explicit operator double(Fraction frac)
{ return frac.ToDouble(); }
public static implicit operator string(Fraction frac)
{ return frac.ToString(); }
/// <summary>
/// checks whether two fractions are equal
/// </summary>
public override bool Equals(object obj)
{
Fraction frac=(Fraction)obj;
return ( Numerator==frac.Numerator && Denominator==frac.Denominator);
}
/// <summary>
/// returns a hash code for this fraction
/// </summary>
public override int GetHashCode()
{
return ( Convert.ToInt32((Numerator ^ Denominator) & 0xFFFFFFFF) ) ;
}
/// <summary>
/// internal function for negation
/// </summary>
private static Fraction Negate(Fraction frac1)
{
long iNumerator=-frac1.Numerator;
long iDenominator=frac1.Denominator;
return ( new Fraction(iNumerator, iDenominator) );
}
/// <summary>
/// internal functions for binary operations
/// </summary>
private static Fraction Add(Fraction frac1, Fraction frac2)
{
try
{
checked
{
long iNumerator=frac1.Numerator*frac2.Denominator + frac2.Numerator*frac1.Denominator;
long iDenominator=frac1.Denominator*frac2.Denominator;
return ( new Fraction(iNumerator, iDenominator) );
}
}
catch(OverflowException)
{
throw new FractionException("Overflow occurred while performing arithemetic operation");
}
catch(Exception)
{
throw new FractionException("An error occurred while performing arithemetic operation");
}
}
private static Fraction Multiply(Fraction frac1, Fraction frac2)
{
try
{
checked
{
long iNumerator=frac1.Numerator*frac2.Numerator;
long iDenominator=frac1.Denominator*frac2.Denominator;
return ( new Fraction(iNumerator, iDenominator) );
}
}
catch(OverflowException)
{
throw new FractionException("Overflow occurred while performing arithemetic operation");
}
catch(Exception)
{
throw new FractionException("An error occurred while performing arithemetic operation");
}
}
/// <summary>
/// The function returns GCD of two numbers (used for reducing a Fraction)
/// </summary>
private static long GCD(long iNo1, long iNo2)
{
// take absolute values
if (iNo1 < 0) iNo1 = -iNo1;
if (iNo2 < 0) iNo2 = -iNo2;
do
{
if (iNo1 < iNo2)
{
long tmp = iNo1; // swap the two operands
iNo1 = iNo2;
iNo2 = tmp;
}
iNo1 = iNo1 % iNo2;
} while (iNo1 != 0);
return iNo2;
}
/// <summary>
/// The function reduces(simplifies) a Fraction object by dividing both its numerator
/// and denominator by their GCD
/// </summary>
public static void ReduceFraction(Fraction frac)
{
try
{
if (frac.Numerator==0)
{
frac.Denominator=1;
return;
}
long iGCD=GCD(frac.Numerator, frac.Denominator);
frac.Numerator/=iGCD;
frac.Denominator/=iGCD;
if ( frac.Denominator<0 ) // if -ve sign in denominator
{
//pass -ve sign to numerator
frac.Numerator*=-1;
frac.Denominator*=-1;
}
} // end try
catch(Exception exp)
{
throw new FractionException("Cannot reduce Fraction: " + exp.Message);
}
}
} //end class Fraction
/// <summary>
/// Exception class for Fraction, derived from System.Exception
/// </summary>
public class FractionException : Exception
{
public FractionException() : base()
{}
public FractionException(string Message) : base(Message)
{}
public FractionException(string Message, Exception InnerException) : base(Message, InnerException)
{}
} //end class FractionException
} //end namespace Mehroz
正如@Tillito在评论中指出的那样，我仔细检查了以下代码：
using System.IO;
using System;
using Mehroz;
class Program
{
static void Main()
{
double d = .5;
string str = new Fraction(d).ToString();
Console.WriteLine(str);
}
}
输出：
1/2
答案 1 :(得分：1)
将代码放入静态类中以创建扩展，然后使用如下代码：
final int NOTIFY_ID = 1002;
String aMessage="";
String name = "my_package_channel";
String id = "my_package_channel_1"; // The user-visible name of the channel.
String description = "my_package_first_channel"; // The user-visible description of the channel.
Intent intent;
PendingIntent pendingIntent;
NotificationCompat.Builder builder;
if (notifManager == null) {
notifManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
}
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
int importance = NotificationManager.IMPORTANCE_HIGH;
NotificationChannel mChannel = notifManager.getNotificationChannel(id);
if (mChannel == null) {
mChannel = new NotificationChannel(id, name, importance);
mChannel.setDescription(description);
notifManager.createNotificationChannel(mChannel);
}
builder = new NotificationCompat.Builder(this, id);
intent = new Intent(this, NotificationReturnSlot.class);
pendingIntent = PendingIntent.getActivity(this, 1, intent, 0);
builder.setContentTitle(aMessage) // required
.setSmallIcon(R.mipmap.ic_launcher)
.setContentText(this.getString(R.string.app_name)) // required
.setAutoCancel(false)
.setContentIntent(pendingIntent)
.setVibrate(new long[]{0L})
;
} else {
builder = new NotificationCompat.Builder(this);
intent = new Intent(this, NotificationReturnSlot.class);
pendingIntent = PendingIntent.getActivity(this, 1, intent, 0);
builder.setContentTitle(aMessage) // required
.setSmallIcon(R.mipmap.ic_launcher)
.setContentText(this.getString(R.string.app_name)) // required
.setAutoCancel(false)
.setContentIntent(pendingIntent)
.setVibrate(new long[]{0L})
.setPriority(Notification.PRIORITY_HIGH);
}
int mId = 1489;
startForeground(mId, builder.build());
预期结果：“ var number = 2.83;
var result = number.ToFractions(4);
”
代码：
2 3/4