{"id":120,"date":"2021-12-22T15:36:46","date_gmt":"2021-12-22T08:36:46","guid":{"rendered":"https:\/\/csharptutorial.net\/?page_id=120"},"modified":"2022-01-10T08:42:08","modified_gmt":"2022-01-10T01:42:08","slug":"csharp-float","status":"publish","type":"page","link":"https:\/\/www.csharptutorial.net\/csharp-tutorial\/csharp-float\/","title":{"rendered":"C# float"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn how to use the C# float types to represent floating-point numbers.<\/p>\n\n\n\n

Introduction to the C# float types<\/h2>\n\n\n\n

To represent real numbers, C# uses the following floating number types: float<\/code>, double<\/code> and decimal<\/code>. The following table shows the characteristics of the floating-point types:<\/p>\n\n\n\n

Float type<\/th>Approximate range<\/th>Precision<\/th>Size<\/th><\/tr><\/thead>
float<\/code><\/td>\u00b11.5 x 10\u221245<\/sup> to \u00b13.4 x 1038<\/sup><\/td>~6-9 digits<\/td>4 bytes<\/td><\/tr>
double<\/code><\/td>\u00b15.0 \u00d7 10\u2212324<\/sup> to \u00b11.7 \u00d7 10308<\/sup><\/td>~15-17 digits<\/td>8 bytes<\/td><\/tr>
decimal<\/code><\/td>\u00b11.0 x 10-28<\/sup> to \u00b17.9228 x 1028<\/sup><\/td>28-29 digits<\/td>16 bytes<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Equality test<\/h3>\n\n\n\n

Since computers only can store the floating-point numbers approximately, it’ll cause unexpected behavior if you attempt to compare two float numbers. <\/p>\n\n\n\n

For example, the following expression should return true<\/code>:<\/p>\n\n\n

0.3<\/span> == 0.1<\/span> + 0.1<\/span> + 01<\/span>;<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
But it returns false<\/code> instead:<\/p>\n\n\n
bool<\/span> result = 0.3<\/span> == 0.1<\/span> + 0.1<\/span> + 01<\/span>;\nConsole.WriteLine(result); \/\/ false<\/span><\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
The reason is that the expression returns a value that is approximately equal to 0.3, not 0.3. See the following:<\/p>\n\n\n
Console.WriteLine(0.1<\/span> + 0.1<\/span> + 0.1<\/span>);<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
0.30000000000000004<\/span><\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Float literals<\/h2>\n\n\n\n
Each float type has a specific literal form. And all float literals can have the digit separator (_<\/code>) to make them more readable.<\/p>\n\n\n\n
float<\/h3>\n\n\n\n
The float literals have the f<\/code> or F<\/code> suffix. For example:<\/p>\n\n\n
float<\/span> rate = 5.2F<\/span>;\nfloat<\/span> amount = 10<\/span>_000.5f<\/span>;<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
double<\/h3>\n\n\n\n
The double literals have no suffix. For example:<\/p>\n\n\n
double<\/span> dimension = 3.14<\/span>\ndouble<\/span> radius = 1<\/span>_000.5<\/span><\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Or with the d<\/code> or D<\/code> suffix like this:<\/p>\n\n\n
double<\/span> dimension = 3.14<\/span>d\ndouble<\/span> radius = 1<\/span>_000.5<\/span>D<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
decimal<\/h3>\n\n\n\n
The decimal literals have m<\/code> or M<\/code> suffix:<\/p>\n\n\n
decimal<\/span> amount = 9.99<\/span>m\ndecimal<\/span> tax = 0.08<\/span>M<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Conversions<\/h2>\n\n\n\n
C# implicitly converts a value of float to double. However, you can use an explicit cast to convert a value from one floating-point type to another.<\/p>\n\n\n\n
Summary<\/h2>\n\n\n\n
  • C# uses the float<\/code>, double<\/code>, and demical<\/code> types to represent real numbers.<\/li>
  • Avoid using the equality operator ==<\/code> to compare two real numbers. <\/li><\/ul>\n
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