The C double and decimal data types retain the specified number of decimal places as truncation

In the project, it is used to take two decimal places by truncation, so the following method is written:

 
/// <summary> 
///  Truncate the numeric value by the specified number of decimal places  
/// </summary> 
/// <param name="d"> The decimal to be truncated </param> 
/// <param name="s"> Decimal places, s Greater than or equal to 0 Less than or equal to 28</param> 
/// <returns></returns> 
public static decimal ToFixed(decimal d, int s) 
{ 
decimal sp = Convert.ToDecimal(Math.Pow(10, s)); 

if (d < 0) 
return Math.Truncate(d) + Math.Ceiling((d - Math.Truncate(d)) * sp) / sp; 
else 
return Math.Truncate(d) + Math.Floor((d - Math.Truncate(d)) * sp) / sp; 
} 

/// <summary> 
///  Truncate a double - precision floating - point value by the specified number of decimal places  
/// </summary> 
/// <param name="d"> The double precision floating point number to truncate </param> 
/// <param name="s"> Decimal places, s Greater than or equal to 0 Less than or equal to 15</param> 
/// <returns></returns> 
public static double ToFixed(double d, int s) 
{ 
double sp = Math.Pow(10, s); 

if (d < 0) 
return Math.Truncate(d) + Math.Ceiling((d - Math.Truncate(d)) * sp) / sp; 
else 
return Math.Truncate(d) + Math.Floor((d - Math.Truncate(d)) * sp) / sp; 
} 

By the way, 1.
The ToString("#.##") methods of double and decimal use 4 rounding 5;
Round(decimal d, int decimals) under the static class System.Math, the rounding method USES "4 rounds 6 into 5 pairs";
The third parameter of Round(decimal d, int decimals, MidpointRounding mode) under Math is the enumeration parameter, indicating how to deal with the intermediate value (5);
The method of static class System. Math: http: / / msdn microsoft. com/zh - cn/library/system math_methods (v = vs. 80)