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Language Basics

namespace operation declaration function declaration let bindings mutable bindings set statement Tuples Arrays Ranges Interpolated strings

Classical Control

if elif else for loop while loop repeat until fixup return fail within apply use qubit allocation borrow qubit allocation Conditional expression

Qubits & Gates

X gate Y gate Z gate H gate S gate T gate Rx rotation Ry rotation Rz rotation CNOT

Measurement

M measurement Reset ResetAll Measure Pauli Measurement result comparison Multi-qubit measurement Basis change before measurement Repeated shots pattern Parity measurement Conditional correction

Adjoint & Controlled

Adjoint application Controlled application Adj + Ctl operation Controlled X Controlled rotation Multi-controlled X Uncomputation Self-adjoint operation Functor composition Power of an operation

Quantum Patterns

Bell state GHZ state Superposition over register Quantum teleportation Phase kickback Deutsch-Jozsa skeleton Grover oracle skeleton Amplitude amplification skeleton Quantum random bit Swap test skeleton

Data & Libraries

Pauli values Result values Complex-like representation Array map pattern Array fold pattern Little-endian register concept Big-endian register concept ApplyToEach ApplyToEachCA DumpMachine diagnostics

Testing & Resource Discipline

AssertMeasurement AssertAllZero Qubit reset discipline Ancilla cleanup Operation specialization Intrinsic operation declaration Native gate wrapper Target profile awareness Classical simulation boundary Resource estimation pattern

Q# Complete Course / Language Basics

function declaration

Learn function declaration in Q# with a construct-specific explanation, a unique example, a practical boundary, and a mastery check.

10 min read • Beginner

function declaration is an atomic Q# topic inside Language Basics. The example below uses the actual construct named by the lesson rather than a generic placeholder.

Focus on what function declaration changes: the input, binding, control path, object state, collection, runtime effect, or language contract. Then alter one value and verify that the behavior changes for a reason specific to this feature.

Topic-specific example

qsharp-01-03-function-declaration.qs

qsharp Try It Live

function Square(x : Int) : Int { return x * x; }

Edge case / engineering note

Change the key input in this Q# example and predict the result first; the named construct should be the reason the behavior changes.

Content source & attribution

Original Syntaxis Content · Original Syntaxis Content

Lesson quizzes

function declaration Mastery Check →

operation declaration