What Is the Best Data Type to Use for Money in C#

What is the best data type to use for money in C#?

As it is described at decimal as:

The decimal keyword indicates a 128-bit data type. Compared to
floating-point types, the decimal type has more precision and a
smaller range, which makes it appropriate for financial and monetary
calculations.

You can use a decimal as follows:

decimal myMoney = 300.5m;

What data type should I use to represent money in C#?

Use System.Decimal:

The Decimal value type represents
decimal numbers ranging from positive
79,228,162,514,264,337,593,543,950,335
to negative
79,228,162,514,264,337,593,543,950,335.
The Decimal value type is appropriate
for financial calculations requiring
large numbers of significant integral
and fractional digits and no round-off
errors. The Decimal type does not
eliminate the need for rounding.
Rather, it minimizes errors due to
rounding.

Neither System.Single (float) nor System.Double (double) are precise enough capable of representing high-precision floating point numbers without rounding errors.

Data Type Money C#

According to Microsoft type mapping guide, SQL Server's Money type is mapped to decimal in C#.

Note: a proper way to make your query is to use parameters, like this:

decimal prix = (decimal)(Qte * prixvente);
decimal prix_ttc = prix * (1 + (tva/ 100M));

String requete = @"UPDATE lc 
                   SET lc.Quantite = @qte, 
                       lc.Prix_HT = @prix,
                       lc.Prix_TTC = @prix_ttc
                   FROM LIGNES_FACTURE as lc
                   JOIN  MM_ARTICLE as art ON lc.ID_Article=art.ID
                   JOIN MM_Facture as f ON lc.ID_Facture=f.ID
                   WHERE art.AR_Ref = @ref 
                     AND f.Ref = @reffacture";
SqlCommand command = new SqlCommand(requete, con);
command.Parameters.Add("@qte", qte);
command.Parameters.Add("@prix", prix);
... // Set other parameters here
command.ExecuteNonQuery();

Best practices for dealing with monetary amounts in C#

You should not use floating point numbers because of rounding errors. The decimal type should suit you.

C# which is the best data type for precision 3?

The decimal type is the best for fixed point math.

From the C# Spec Section 4.1.7:

Contrary to the float and double data
types, decimal fractional numbers such
as 0.1 can be represented exactly in
the decimal representation. In the
float and double representations, such
numbers are often infinite fractions,
making those representations more
prone to round-off errors.

Best data type to store money values in MySQL

Since money needs an exact representation don't use data types that are only approximate like float. You can use a fixed-point numeric data type for that like

decimal(15,2)

• 15 is the precision (total length of value including decimal places)
• 2 is the number of digits after decimal point

See MySQL Numeric Types:

These types are used when it is important to preserve exact precision, for example with monetary data.

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