[#wallet-CoinSelectionParams-2constructor-02]
= xref:wallet.adoc[wallet]::xref:wallet/CoinSelectionParams.adoc[CoinSelectionParams]::CoinSelectionParams
:relfileprefix: ../../
:mrdocs:

Construct coin selection parameters with fully specified fees and sizes.

== Synopsis

Declared in `<wallet/coinselection.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
CoinSelectionParams(
    xref:FastRandomContext.adoc[FastRandomContext]& rng_fast,
    int change_output_size,
    int change_spend_size,
    xref:CAmount.adoc[CAmount] min_change_target,
    xref:CFeeRate.adoc[CFeeRate] effective_feerate,
    xref:CFeeRate.adoc[CFeeRate] long_term_feerate,
    xref:CFeeRate.adoc[CFeeRate] discard_feerate,
    int tx_noinputs_size,
    bool avoid_partial,
    std::optional<int> max_tx_weight = std::nullopt);
----

== Parameters

[cols="1,4"]
|===
| Name| Description
| *rng_fast*
| Randomness source to use during coin selection.
| *change_output_size*
| Size of a change output in bytes.
| *change_spend_size*
| Size of the input spending a change output in virtual bytes.
| *min_change_target*
| Minimum change to target in the Knapsack solver and CoinGrinder.
| *effective_feerate*
| Targeted feerate of the transaction being built.
| *long_term_feerate*
| Feerate estimate for spending the change output in the future.
| *discard_feerate*
| Feerate below which spending a change output is not worthwhile.
| *tx_noinputs_size*
| Size of the transaction before inputs and change are added.
| *avoid_partial*
| Whether to spend all or none of the outputs sharing an address.
| *max_tx_weight*
| Optional maximum weight for the transaction.
|===


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