Modern Math SubChecked

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SubChecked

Subtracts two integers, returning an empty Optional if the result would overflow.

Syntax

SubChecked( byval a as T, byval b as T ) as Optional( of T )

Notes

• Returns an Optional: empty means the true result does not fit in T. The overflow is reported rather than wrapped, which is what a - b does silently.
• The check happens before the operation, so nothing undefined occurs on the way to finding out.
• SubSaturating clamps instead, and SubWrapping wraps on purpose.

Examples

#import "std/outcome"
#import "std/numeric"
using numeric, outcome

dim as int8 a = 100, b = 100

var r = SubChecked( a, b )
print r.HasValue( )          '' false -- 200 does not fit in a BYTE

dim as int8 small = 1
var ok = SubChecked( small, small )
print ok.HasValue( )         '' true
print ok.Value( )

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Library: Math Library
Category: Math Library
Documented under: Members