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The float keyword denotes a simple type that stores 32-bit floating-point values. The following table shows the precision and approximate range for the float type.

Type Approximate range Precision .NET Framework type
float ±1.5 × 10−45 to ±3.4 × 1038 7 digits System.Single


By default, a real numeric literal on the right-hand side of the assignment operator is treated as double. Therefore, to initialize a float variable use the suffix f or F, for example:

float x = 3.5F;

If you don't use the suffix in the previous declaration, you will get a compilation error because you are attempting to store a double value into a float variable.


You can mix numeric integral types and floating-point types in an expression. In this case, the integral types are converted to floating-point types. The evaluation of the expression is performed according to the following rules:

  • If one of the floating-point types is double, the expression evaluates to double (or bool in the case of relational or Boolean expressions).
  • If there is no double type in the expression, the expression evaluates to float (or bool in the case of relational or Boolean expressions).

A floating-point expression can contain the following sets of values:

  • Positive and negative zero
  • Positive and negative infinity
  • Not-a-Number value (NaN)
  • The finite set of nonzero values

For more information on these values, refer to IEEE Standard for Binary Floating-Point Arithmetic, available on the Web site

For more information on floating-point value sets, see 4.1.5 Floating point types.


In the following example, an int, a short, and a float are included in a mathematical expression giving a float result (notice that there is no double in the expression).

// keyword_float.cs
// Mixing types in expressions
using System;
class MixedTypes 
   public static void Main() 
      int x = 3;
      float y = 4.5f;
      short z = 5;
      Console.WriteLine("The result is {0}", x*y/z); 


The result is 2.7

See Also

C# Keywords | Default Values Table | Built-in Types Table | Floating-Point Types Table | Implicit Numeric Conversions Table | Explicit Numeric Conversions Table | Single Structure