NAME¶

std::isless - std::isless

Synopsis¶

Defined in header <cmath>
bool isless( float x, float y );
(since C++11)
bool isless( double x, double y ); (until C++23)

bool isless( long double x, long double y );
constexpr bool isless( /* floating-point-type */ x, (1)
/* floating-point-type */ y (since C++23)
);
Additional overloads
Defined in header <cmath>
template< class Arithmetic1, class Arithmetic2 > (A) (since C++11)
bool isless( Arithmetic1 x, Arithmetic2 y ); (constexpr since C++23)

1) Determines if the floating point number x is less than the floating-point number
y, without setting floating-point exceptions.
The library provides overloads for all cv-unqualified floating-point types as the
type of the parameters x and y.
(since C++23)
A) Additional overloads are provided for all other combinations of arithmetic types.

Parameters¶

x, y - floating-point or integer values

Return value¶

true if x < y, false otherwise.

Notes¶

The built-in operator< for floating-point numbers may raise FE_INVALID if one or
both of the arguments is NaN. This function is a "quiet" version of operator<.

The additional overloads are not required to be provided exactly as (A). They only
need to be sufficient to ensure that for their first argument num1 and second
argument num2:

* If num1 or num2 has type long double, then std::isless(num1, num2)
has the same effect as std::isless(static_cast<long double>(num1),
static_cast<long double>(num2)).
* Otherwise, if num1 and/or num2 has type double or an integer type,
then std::isless(num1, num2) has the same effect as (until C++23)
std::isless(static_cast<double>(num1),
static_cast<double>(num2)).
* Otherwise, if num1 or num2 has type float, then std::isless(num1,
num2) has the same effect as std::isless(static_cast<float>(num1),
static_cast<float>(num2)).
If num1 and num2 have arithmetic types, then std::isless(num1, num2)
has the same effect as std::isless(static_cast</*
common-floating-point-type */>(num1),
static_cast</* common-floating-point-type */>(num2)),
where /* common-floating-point-type */ is the floating-point type with
the greatest floating-point conversion rank and greatest
floating-point conversion subrank between the types of num1 and num2, (since C++23)
arguments of integer type are considered to have the same
floating-point conversion rank as double.

If no such floating-point type with the greatest rank and subrank
exists, then overload resolution does not result in a usable candidate
from the overloads provided.

See also¶

less function object implementing x < y
(class template)
isgreater checks if the first floating-point argument is greater than the second
(C++11) (function)
C documentation for
isless