CODEWITHSUNDEEP
c++c++11stlstandard-library
Muhammad
Muhammad

Reputation: 1655

numeric_limits lowest and min member functions

numeric_limits<T>::min();
numeric_limits<T>::lowest();

What is the different between the value returned by both functions?

Upvotes: 40

Views: 12356

Answers (2)

filmor
filmor

Reputation: 32212

For floating point types min returns the smallest finite number that is > 0 representable in the type (i.e. the number having the lowest absolute value != 0) while lowest returns the smallest finite number that is representable (i.e. the negative number of maximal absolute value that is greater than -infinity).

Upvotes: 17

Andy Prowl
Andy Prowl

Reputation: 126432

Paragraph 18.3.2.4 of the C++11 Standard specifies:

static constexpr T min() noexcept;

1 Minimum finite value.

2 For floating types with denormalization, returns the minimum positive normalized value.

3 Meaningful for all specializations

[...]

static constexpr T lowest() noexcept;

6 A finite value x such that there is no other finite value y where y < x.

7 Meaningful for all specializations in which is_bounded != false.

Footnote 197 then adds the relevant remark:

lowest() is necessary because not all floating-point representations have a smallest (most negative) value that is the negative of the largest (most positive) finite value.

Upvotes: 29

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