is_void

Applicability

Product	Supported
Atlas 350 Accelerator Card	√
Atlas A3 training product/Atlas A3 inference product	√
Atlas A2 training product/Atlas A2 inference product	√
Atlas 200I/500 A2 inference product	x
Atlas inference product AI Core	x
Atlas inference product Vector Core	x
Atlas training product	x

Function Usage

Checks whether a type is the void type during program compilation. This API can be used for type checking and conditional processing during compilation.

Prototype

template <typename Tp>
struct is_void;

Parameters

**Table 1** Template parameters
Parameter	Description
Tp	Types to be checked, including basic data types, composite data types, modifier types, template classes, and user-defined types

Restrictions

None

Returns

The static constant member value of is_void is used to obtain the returned Boolean value. The values of is_void<Tp>::value are as follows:

true: Tp is of the void type.
false: Tp is not of the void type.

Examples

// Custom test type
struct MyStruct{};

// Function of the void type
using FuncType = void(int);

// Mismatch scenario
AscendC::printf("AscendC::Std::is_void::value:%d\n", AscendC::Std::is_void<int>::value);
AscendC::printf("AscendC::Std::is_void::value:%d\n", AscendC::Std::is_void<void*>::value);
AscendC::printf("AscendC::Std::is_void::value:%d\n", AscendC::Std::is_void<FuncType>::value);
AscendC::printf("AscendC::Std::is_void::value:%d\n", AscendC::Std::is_void<MyStruct>::value);

// Matching scenario
AscendC::printf("AscendC::Std::is_void::value:%d\n", AscendC::Std::is_void<void>::value);
AscendC::printf("AscendC::Std::is_void::value:%d\n", AscendC::Std::is_void<const void>::value);
AscendC::printf("AscendC::Std::is_void::value:%d\n", AscendC::Std::is_void<volatile void>::value);
AscendC::printf("AscendC::Std::is_void::value:%d\n", AscendC::Std::is_void<const volatile void>::value);

// Execution result
AscendC::Std::is_void::value:0
AscendC::Std::is_void::value:0
AscendC::Std::is_void::value:0
AscendC::Std::is_void::value:0
AscendC::Std::is_void::value:1
AscendC::Std::is_void::value:1
AscendC::Std::is_void::value:1
AscendC::Std::is_void::value:1

Parent topic: Type Traits