std::numeric_limits<T>::traps

The value of std::numeric_limits::traps is true for all arithmetic types T that have at least one value at the start of the program that, if used as an argument to an arithmetic operation, will generate a trap.

# Declarations

static const bool traps;

(until C++11)

static constexpr bool traps;

(since C++11)

# Notes

On most platforms integer division by zero always traps, and std::numeric_limits::traps is true for all integer types that support the value 0. The exception is the type bool: even though division by false traps due to integral promotion from bool to int, it is the zero-valued int that traps. Zero is not a value of type bool.

On most platforms, floating-point exceptions may be turned on and off at run time (e.g. feenableexcept() on Linux or _controlfp on Windows), in which case the value of std::numeric_limits::traps for floating-point types reflects the state of floating-point trapping facility at the time of program startup, which is false on most modern systems. An exception would be a DEC Alpha program, where it is true if compiled without -ieee.

# Example

#include <iostream>
#include <limits>
 
int main()
{
    std::cout << std::boolalpha
              << "bool:     traps = " << std::numeric_limits<bool>::traps << '\n'
              << "char:     traps = " << std::numeric_limits<char>::traps << '\n'
              << "char16_t: traps = " << std::numeric_limits<char16_t>::traps << '\n'
              << "long:     traps = " << std::numeric_limits<long>::traps << '\n'
              << "float:    traps = " << std::numeric_limits<float>::traps << '\n';
}

# Defect reports

# See also

• Floating-point environment
• tinyness_before
• has_denorm_loss