strong_ordering Class

Detailed Description

A value of type Qt::strong_ordering is typically returned from a three-way comparison function. Such a function compares two objects and establishes how they are ordered. It uses this return type to indicate that the ordering is strict; that is, the function establishes a well-defined total order.

Qt::strong_ordering has four values, represented by the following symbolic constants:

• less represents that the left operand is less than the right;
• equal represents that the left operand is equivalent to the right;
• equivalent is an alias for equal;
• greater represents that the left operand is greater than the right.

Qt::strong_ordering is idiomatically used by comparing an instance against a literal zero, for instance like this:

 // given a, b, c, d as objects of some type that allows for a 3-way compare,
 // and a compare function declared as follows:

 Qt::strong_ordering compare(T lhs, T rhs); // defined out-of-line
 ~~~

 Qt::strong_ordering result = compare(a, b);
 if (result < 0) {
     // a is less than b
 }

 if (compare(c, d) >= 0) {
     // c is greater than or equal to d
 }