Implicit and Explicit Type of Conversion

Implicit Type Conversions

• A widening conversion is one in which an object is converted to a type that can include at least approximations to all of the values of the original type.
• A narrowing conversion is one that converts an object to a type that cannot include all of the values of the original type e.g., float to int.
• A mixed-mode expression is one that has operands of different types.
• Coercion is an implicit type conversion.

Explicit Type Conversions

• Called casting in C-based language

Examples

• C: (int) angle
• Ada: Float (sum)

Note: that Ada’s syntax is similar to function calls

Disadvantage of coercion:

• They decrease in the type error detection ability of the compiler.
• In most languages, all numeric types are coerced in expressions, using widening conversions.
• In Ada, there are virtually no coercion in expressions