Explicit Type Conversions

Let’s talk about explicit type conversions.

As you have seen earlier in this chapter, there are cases where automatic conversions are not available:

  • Conversions from wider types to narrower types
  • Conversions from const to mutable
  • immutable conversions
  • Conversions from integers to enum values

If such a conversion is known to be safe, the programmer can explicitly ask for a type conversion by one of the following methods:

  • Construction syntax
  • std.conv.tofunction
  • std.exception.assumeUniquefunction
  • cast operator

Construction syntax

The struct and class construction syntax is available for other types as well:

DestinationType(value)

For example, the following conversion makes a double value from an int value, presumably to preserve the fractional part of the division operation:

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