Type testing

Sometimes you want to check the type used to create a template. The standard library provides some handy routines to do this (defined in the file <type_traits>), like:

• std::is_arithmetic<T> – this is true if the type is floating point or integral data type (like int, unsigned short, float or double). Example:
• Using is_arithmetic

  C++

  bool value1 = std::is_arithmetic<int>::value; // true bool value2 = std::is_arithmetic<int*>::value; // false bool value3 = std::is_arithmetic<bool>::value; // false bool value4 = std::is_arithmetic<double>::value; // true

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  bool value1 = std::is_arithmetic<int>::value; // true bool value2 = std::is_arithmetic<int*>::value; // false bool value3 = std::is_arithmetic<bool>::value; // false bool value4 = std::is_arithmetic<double>::value; // true

• std::is_integral<T> – this is true if the type is an integral data type (like int, unsigned short, bool,  char or long). Example:
• Using is_arithmetic

  C++

  bool value1 = std::is_integral<int>::value; // true bool value2 = std::is_integral<int*>::value; // false bool value3 = std::is_integral<bool>::value; // true bool value4 = std::is_integral<double>::value; // false

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  bool value1 = std::is_integral<int>::value; // true bool value2 = std::is_integral<int*>::value; // false bool value3 = std::is_integral<bool>::value; // true bool value4 = std::is_integral<double>::value; // false

• std::is_floating_point<T> – this is true if the type is floating point type (float, double or long double). Example:
• Using is_arithmetic

  C++

  bool value1 = std::is_arithmetic<float>::value; // true bool value2 = std::is_arithmetic<int>::value; // false bool value3 = std::is_arithmetic<bool>::value; // false bool value4 = std::is_arithmetic<long double>::value; // true

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  bool value1 = std::is_arithmetic<float>::value; // true bool value2 = std::is_arithmetic<int>::value; // false bool value3 = std::is_arithmetic<bool>::value; // false bool value4 = std::is_arithmetic<long double>::value; // true