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Comparative expressions

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Equality comparisons

Equality comparisons (==) and inequality comparisons (!=) are currently limited to the following data types: Int, BigInt, Double, String, Bool, Result, Pauli, and Qubit. Equality comparisons of struct types and callables are currently not supported.

Equality comparison for values of type Qubit evaluates whether the two expressions identify the same qubit. There is no notion of a quantum state in Q#; equality comparison, in particular, does not access, measure, or modify the quantum state of the qubits.

Equality comparisons for Double values may be misleading due to rounding effects. For instance, the following comparison evaluates to false due to rounding errors: 49.0 * (1.0/49.0) == 1.0.

Equality comparison of arrays, and tuples are supported by comparisons of their items, and are only supported if all of their nested types support equality comparison.

Equality comparison of close-ended ranges are supported, and two ranges are considered equal if they produce the same sequence of integers. For example, the following two ranges

    let r1 = 0..2..5; // generates the sequence 0,2,4
    let r2 = 0..2..4; // generates the sequence 0,2,4

are considered equal. Equality comparison of open-ended ranges are not supported.

Quantitative comparison

The operators less-than (<), less-than-or-equal (<=), greater-than (>), and greater-than-or-equal (>=) define quantitative comparisons. They can only be applied to data types that support such comparisons, that is, the same data types that can also support arithmetic expressions.