is_const

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 const type during program compilation. This API can be used for type checking and conditional processing during compilation.

Prototype

template <typename Tp>
struct is_const;

Parameters

**Table 1** Template parameters
Parameter	Description
Tp	Types to be checked, including basic types (such as int and float), composite types (such as array, pointer, and reference), user-defined types (such as class and struct), and const-qualified types

Restrictions

None

Returns

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

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

Examples

// Custom test type
struct MyStruct{int val;};

// Mismatch scenario
AscendC::printf("AscendC::Std::is_const::value:%d\n", AscendC::Std::is_const<int>::value);
AscendC::printf("AscendC::Std::is_const::value:%d\n", AscendC::Std::is_const<const int*>::value);
AscendC::printf("AscendC::Std::is_const::value:%d\n", AscendC::Std::is_const<int&>::value);
AscendC::printf("AscendC::Std::is_const::value:%d\n", AscendC::Std::is_const<const int&>::value);
AscendC::printf("AscendC::Std::is_const::value:%d\n", AscendC::Std::is_const<int&&>::value);
AscendC::printf("AscendC::Std::is_const::value:%d\n", AscendC::Std::is_const<int[5]>::value);
AscendC::printf("AscendC::Std::is_const::value:%d\n", AscendC::Std::is_const<double>::value);
AscendC::printf("AscendC::Std::is_const::value:%d\n", AscendC::Std::is_const<MyStruct>::value);
AscendC::printf("AscendC::Std::is_const::value:%d\n", AscendC::Std::is_const<void>::value);

// Matching scenario
AscendC::printf("AscendC::Std::is_const::value:%d\n", AscendC::Std::is_const<const int>::value);
AscendC::printf("AscendC::Std::is_const::value:%d\n", AscendC::Std::is_const<int const>::value);
AscendC::printf("AscendC::Std::is_const::value:%d\n", AscendC::Std::is_const<int* const>::value);
AscendC::printf("AscendC::Std::is_const::value:%d\n", AscendC::Std::is_const<const int[5]>::value);
AscendC::printf("AscendC::Std::is_const::value:%d\n", AscendC::Std::is_const<const volatile double>::value);
AscendC::printf("AscendC::Std::is_const::value:%d\n", AscendC::Std::is_const<const MyStruct>::value);

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

Parent topic: Type Traits