Export (0) Print
Expand All

7.9.2 Floating-point comparison operators

Visual Studio .NET 2003

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 IEEE 754 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. For example, if either of x and y is NaN, then x < y is false, but !(x >= y) is true.
  • When neither operand is NaN, the operators compare the values of the two floating-point operands with respect to the ordering
    –8 < –max < ... < –min < –0.0 == +0.0 < +min < ... < +max < +8
    

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:

  • Negative and positive zeros are considered equal.
  • A negative infinity is considered less than all other values, but equal to another negative infinity.
  • A positive infinity is considered greater than all other values, but equal to another positive infinity.
Show:
© 2015 Microsoft