Real Literals

<-- Integer LiteralsCharacter Literals -->

Syntax:

<decimal-digits>.<decimal-digits>[exponent-part][real-type-suffix]
.<decimal-digits>[exponent-part][real-type-suffix]
<decimal-digits><exponent-part>[real-type-suffix]
<decimal-digits><real-type-suffix>

Exponent-part:

e|E[+|-]<decimal-digits>
  • The literals can be used in either line of the syntax.
  • If no suffix is specified, the default type of the literal is double.
  • F or f suffix can be used in float literals, for example, 1.5e3F.
  • D or d suffix can be used in double literals, for example, .3456E-5D.
  • M or m suffix can be used in decimal literals, for example, 7e-8M.
Note Note
Hexadecimal is not allowed to be used in float literals, double literals or decimal literals.

Note Note
If the literal is outside of the range of the indicated type, a compile-time error will occur.

See the following real literal examples and the comments.

3.78915       // Legal, no suffix so it is double type
12345E-3F     // Legal, so it is a float literal
321E          // Illegal, the exponent part is incomplete
210f          // Legal, check the last line of the syntax
.e55          // Illegal, missing fraction part, the digits following dot is a must
77e3          // Legal, check the third line of the syntax

Example 01-19-01:

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using System;

namespace TestRealLiterals
{
    class Program
    {
        static void Main(string[] args)
        {
            decimal m = 1234E1M;
            double d = 5678E-3D;
            //float f = 3.14;
            float f = 3.14f;

            Console.WriteLine("f={0}", f);
            Console.WriteLine("m+d={0}", (double)m+d);
            Console.WriteLine("m+d={0}", m+(decimal)d);

            Console.Read();
        }
    }
}

Output

f=3.14
m+d=12345.678
m+d=12345.678
  • Line 9-10: A decimal and a double variable are defined and assigned.
  • Line 11: If this line is not commented out, you will get a "Literal of type double cannot be implicitly converted to type 'float'" compile error. Because the default literal value without suffix owns a double type.
  • Line 12: That's correct assignment by adding a suffix at the end of the literal.
  • Line 14: Output the float variable value.
  • Line 15-16: Output the addition result. You'll have to cast explicitly to the same type then do the addition.
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