The predefined floating-point comparison operators are:
bool operator ==(float x, float y);
bool operator ==(double x, double y);
bool operator !=(float x, float y);
bool operator !=(double x, double y);
bool operator <(float x, float y);
bool operator <(double x, double y);
bool operator >(float x, float y);
bool operator >(double x, double y);
bool operator <=(float x, float y);
bool operator <=(double x, double y);
bool operator >=(float x, float y);
bool operator >=(double x, double y);
The operators compare the operands according to the rules of the IEC 60559 standard:
If either operand is NaN, the result is false for all operators except !=, for which the result is true. For
any two operands, x != y always produces the same result as !(x == y). However, when one or both
operands are NaN, the <, >, <=, and >= operators do not produce the same results as the logical negation of
the opposite operator. [Example: If either of x and y is NaN, then x < y is false, but !(x >= y) is true.
end example]
• When neither operand is NaN, the operators compare the values of the two floating-point operands with
respect to the ordering
–∞ < –max < … < –min < –0.0 == +0.0 < +min < … < +max < +∞
where min and max are the smallest and largest positive finite values that can be represented in the given
floating-point format. Notable effects of this ordering are:
o Negative and positive zeros are considered equal.
o A negative infinity is considered less than all other values, but equal to another negative infinity.
o A positive infinity is considered greater than all other values, but equal to another positive infinity.
Lifted (§14.2.7) forms of the unlifted predefined floating-point comparison operators defined above are also predefined.
