Description
For one-based positions return length minus index; for zero-based positions return length minus one minus index.
An index map tracks where one item lands after a structural list operation. Zero-based element positions differ from boundary cursors, and missing destinations need a sentinel.
For one-based positions return length minus index; for zero-based positions return length minus one minus index.
When to use this tool
Use List Index Distance From End when you need one item's position under an explicit list transformation.
How to use the tool and how it works
- Enter length, index, oneBased. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read distance. Use the output convention below.
For one-based positions return length minus index; for zero-based positions return length minus one minus index.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| length | Length, count, or code length under the stated domain and unit convention. | Required. Safe integer; minimum 1. |
| index | Zero-based position or diagnostic index under the calculation above; inspect any sentinel policy. | Required. Safe integer. |
| oneBased | One Based | Required. Boolean. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| distance | Distance | Required. Safe integer. |
{
"input": {
"length": 8,
"index": 3,
"oneBased": false
},
"output": {
"distance": 4
}
}Limitations and assumptions
- This counts elements after the selected position, not distance to an exclusive terminal boundary.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Apply the operation to a small representative list when checking a consuming language's indexing and slicing semantics.
References
Similar or alternative tools
- List: List Negative Index Resolver
Add length to a negative index and retain nonnegative indices.
- List Anchor Relative Index Sign
Subtract anchor from index using exact integers and return decimal distance plus a separate sign comparison.