43 lines
1.4 KiB
Plaintext
43 lines
1.4 KiB
Plaintext
:sig
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u64 DValue::to_u64(u64 default_value = 0) const
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:params
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default_value : returned when the value is missing or cannot be parsed as a number
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return value : the value as an unsigned 64-bit integer, or `default_value`
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:see
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>types
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0_DValue
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json_decode
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int_val
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to_bool
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to_s64
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to_f64
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:content
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Reads a `DValue` value as an unsigned integer. This is a read accessor: it is `const`, never creates or modifies nodes, and dereferences internal references automatically.
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String values are trimmed and parsed permissively, like `to_s64()`. Boolean values become `1` or `0`. Negative values clamp to `0`, and results above the `u64` range clamp to the maximum.
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`default_value` is returned when:
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- the node is unset or holds an empty string
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- the string does not parse as a number
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- the node is map-shaped with more than one entry, or an unresolvable reference
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A map-shaped node with exactly one entry unwraps to that entry's value before converting. Note that a *present* negative value clamps to `0` rather than returning the default — the default signals "missing or unparseable", not "out of range".
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## Example
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```cpp
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u64 limit = context.get["limit"].to_u64(50);
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u64 owner_id = row.get_by_path("owner/id").to_u64();
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```
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Use this for counts, identifiers, limits, timestamps, and other non-negative numeric values stored inside a `DValue`.
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## Related Concepts
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- PHP: `intval()` with a fallback
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- JavaScript: `parseInt(x) || fallback` (within unsigned range)
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