C# Language Specification

User-defined explicit conversions

A user-defined explicit conversion consists of an optional standard explicit conversion, followed by execution of a user-defined implicit or explicit conversion operator, followed by another optional standard explicit conversion. The exact rules for evaluating user-defined explicit conversions are described in §6.4.5.

3. Standard conversions

The standard conversions are those pre-defined conversions that can occur as part of a user-defined conversion.

1. Standard implicit conversions

The following implicit conversions are classified as standard implicit conversions:

• 
  Identity conversions (§6.1.1)
  
• 
  Implicit numeric conversions (§6.1.2)
  
• 
  Implicit nullable conversions (§6.1.4)
  
• 
  Implicit reference conversions (§6.1.6)
  
• 
  Boxing conversions (§6.1.7)
  
• 
  Implicit constant expression conversions (§6.1.8)
  
• 
  Implicit conversions involving type parameters (§6.1.10)
  

The standard implicit conversions specifically exclude user-defined implicit conversions.

2.