> For the complete documentation index, see [llms.txt](https://whisky.sidan.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://whisky.sidan.io/tx-builder/getting-started/lock-fund.md).

# Lock Fund

### Build a transaction to send funds to a smart contract

The following shows a simple example of building a transaction to lock fund in a smart contact.

```rust
use whisky::*;

pub fn lock_fund(
    script_address: &str,
    datum: &str,
    my_address: &str,
    inputs: &[UTxO],
) -> Result<String, WError> {
    let mut tx_builder = TxBuilder::new_core();
    tx_builder
        .tx_out(script_address, &[])
        .tx_out_inline_datum_value(&WData::JSON(datum.to_string())) // JSON string datum
        // .tx_out_datum_hash_value(WData::JSON(datum.to_string())) // Datum hash
        .change_address(my_address)
        .select_utxos_from(inputs, 5000000)
        .complete_sync(None)?;

    Ok(tx_builder.tx_hex())
}
```