High

// Generated Code Library declaration:
function High: Int64;

// Effective call contract:
function High(X): Int64;

Example

procedure ScriptEvent(var Value: variant);
begin
  Value := High('Velox'); // 5
end;

Usage

Parameters

Name	Type	Description
X	supported value	Dynamic/static array, string or supported integer value whose value type/range is inspected.

Pass a value or variable. Unlike Velox's intrinsic syntax, this function is not documented to accept a bare type identifier such as High(Integer).

Returns

Runtime argument type	Result
Dynamic array	Length(X) - 1; -1 when empty
Static array	declared start offset plus element count minus one
String	Length(X); 0 when empty
Byte / ShortInt	255 / 127
Word / SmallInt	65535 / 32767
Cardinal / Integer	4294967295 / 2147483647
Int64	9223372036854775807
UInt64	-1 because the unsigned maximum is written unchecked into the declared Int64 slot

Additional Technical Info

High returns the upper index of a supported array/string value or the maximum value for one of the supported integer storage types.

The generated declaration is incomplete: the compiler adds a required untyped argument named X after creating the displayed declaration. This runtime helper is narrower than Delphi's compiler intrinsic. The example is fictional and source-reviewed only.

Implementation

1. The compiler adds the synthetic input parameter to the declaration.
2. Runtime High_ resolves its type with NewTPSVariantIFC.
3. Arrays/strings use runtime length/type metadata; integer branches use the host type constants.
4. A matching signed/unsigned stack setter writes into the declared Int64 result slot.
5. Unsupported base types return failure and become a script call/type error.

Edge cases and differences from Delphi

• Empty dynamic arrays return -1; empty strings return 0 because Velox strings are one-based (Low(String)=1).
• High(UInt64) puts the unsigned all-bits-one value into the declared Int64 return slot. PascalScript.inc disables range checks, so the bit pattern is interpreted as signed -1 rather than raising or returning 18446744073709551615.
• Characters, enumerations, sets, Variants, objects and pointers are not branches in High_. Enumerations therefore do not get their declared last member.
• The value of a numeric argument is irrelevant; only its PascalScript base type selects the constant.
• Dynamic array length is inspected at call time. A concurrent mutation of shared array storage is not synchronized.
• The Delphi reference describes a broader intrinsic whose result type follows its argument. Velox instead fixes the public return to Int64.

Side effects

The function does not mutate X, but ordinary argument expressions are evaluated before the call.

Related entries

• Low returns the corresponding lower index/type limit.
• MaxIntValue examines actual values in an Integer array rather than a type boundary.

External references

• Free Pascal: System.High
• Embarcadero DocWiki: System.High

Created 2026-07-15