qiskit.circuit.InstructionSet.c_if

InstructionSet.c_if(classical, val)

Set a classical equality condition on all the instructions in this set between the ClassicalRegister or Clbit classical and value val.

Note

This is a setter method, not an additive one. Calling this multiple times will silently override any previously set condition on any of the contained instructions; it does not stack.

Parameters

• classical (Clbit | ClassicalRegister | int) -- the classical resource the equality condition should be on. If this is given as an integer, it will be resolved into a Clbit using the same conventions as the circuit these instructions are attached to.

• val (int) -- the value the classical resource should be equal to.

Returns

This same instance of InstructionSet, but now mutated to have the given equality condition.

Raises

CircuitError -- if the passed classical resource is invalid, or otherwise not resolvable to a concrete resource that these instructions are permitted to access.

Return type

InstructionSet

Example

from qiskit import ClassicalRegister, QuantumRegister, QuantumCircuit

qr = QuantumRegister(2)
cr = ClassicalRegister(2)
qc = QuantumCircuit(qr, cr)
qc.h(range(2))
qc.measure(range(2), range(2))

# apply x gate if the classical register has the value 2 (10 in binary)
qc.x(0).c_if(cr, 2)

# apply y gate if bit 0 is set to 1
qc.y(1).c_if(0, 1)

qc.draw('mpl')

(Source code)