using System;
double value = 1.234;
Console.WriteLine(*"ROUND: {0}"*, Math.Round(value));ROUND: 1

Overload

double

decimal

enum

using System;
*//*
*// Round double type in three ways.*
*//*
double before1 = 123.45;
double after1 = Math.Round(before1, 1, MidpointRounding.AwayFromZero); *// Rounds "up"*
double after2 = Math.Round(before1, 1, MidpointRounding.ToEven); *// Rounds to even*
double after3 = Math.Round(before1);
Console.WriteLine(before1); *// Original*
Console.WriteLine(after1);
Console.WriteLine(after2);
Console.WriteLine(after3);
*//*
*// Round decimal type.*
*//*
decimal before2 = 125.101M;
decimal after4 = Math.Round(before2);
decimal after5 = Math.Round(before2, 1);
Console.WriteLine(before2); *// Original*
Console.WriteLine(after4);
Console.WriteLine(after5);123.45
123.5
123.4
123
125.101
125
125.1

using System;
for (double i = 0.1; i < 0.99; i += 0.1)
{
Console.WriteLine(*"{0}=({1},{2})"*, i,
Math.Round(i, MidpointRounding.ToEven),
Math.Round(i, MidpointRounding.AwayFromZero));
}0.1=(0,0)
0.2=(0,0)
0.30000000000000004=(0,0)
0.4=(0,0)
0.5=(0,1)
0.6=(1,1)
0.7=(1,1)
0.7999999999999999=(1,1)
0.8999999999999999=(1,1)

using System;
using System.Diagnostics;
const int _max = 100000000;
*// Version 1: use Math.Round with argument of 0.*
var s1 = Stopwatch.StartNew();
for (int i = 0; i < _max; i++)
{
double d = Math.Round(1.3665, 0);
if (d == 1.5)
{
throw new Exception();
}
}
s1.Stop();
*// Version 2: use Math.Round with argument of 1.*
var s2 = Stopwatch.StartNew();
for (int i = 0; i < _max; i++)
{
double d = Math.Round(1.3665, 1);
if (d == 1.5)
{
throw new Exception();
}
}
s2.Stop();
Console.WriteLine(((double)(s1.Elapsed.TotalMilliseconds * 1000000) / _max).ToString(*"0.00 ns"*));
Console.WriteLine(((double)(s2.Elapsed.TotalMilliseconds * 1000000) / _max).ToString(*"0.00 ns"*));5.52 ns Math.Round, 0
4.91 ns Math.Round, 1

if

Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.

Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.

This page was last updated on May 19, 2023 (edit).