# UParseError

A [UParseError](https://developer.android.com/ndk/reference/struct/u-parse-error#struct_u_parse_error) struct is used to returned detailed information about parsing errors.

## Summary

It is used by ICU parsing engines that parse long rules, patterns, or programs, where the text being parsed is long enough that more information than a UErrorCode is needed to localize the error.

The line, offset, and context fields are optional; parsing engines may choose not to use to use them.

The preContext and postContext strings include some part of the context surrounding the error. If the source text is "let for=7" and "for" is the error (e.g., because it is a reserved word), then some examples of what a parser might produce are the following:


```text
preContext   postContext
""           ""            The parser does not support context
"let "       "=7"          Pre- and post-context only
"let "       "for=7"       Pre- and post-context and error text
""           "for"         Error text only
```

<br />

Examples of engines which use [UParseError](https://developer.android.com/ndk/reference/struct/u-parse-error#struct_u_parse_error) (or may use it in the future) are Transliterator, RuleBasedBreakIterator, and RegexPattern.

<br />

| ### Public attributes ||
|---|---|
| `https://developer.android.com/ndk/reference/struct/u-parse-error#struct_u_parse_error_1a7e97bc264516d0eecda03609162db2a2` | `int32_t` The line on which the error occurred. |
| `https://developer.android.com/ndk/reference/struct/u-parse-error#struct_u_parse_error_1aa18e9bc2d82bd5a513aa489b32248f69` | `int32_t` The character offset to the error. |
| `https://developer.android.com/ndk/reference/struct/u-parse-error#struct_u_parse_error_1a1076f681e0c1fcec4bf0ff28703b9aea[U_PARSE_CONTEXT_LEN]` | `https://developer.android.com/ndk/reference/group/icu4c#group__icu4c_1ga6bb9fad572d65b305324ef288165e2ac` The error itself and/or textual context after the error. |
| `https://developer.android.com/ndk/reference/struct/u-parse-error#struct_u_parse_error_1a3f7f2e98b8105346b87170866970c85a[U_PARSE_CONTEXT_LEN]` | `https://developer.android.com/ndk/reference/group/icu4c#group__icu4c_1ga6bb9fad572d65b305324ef288165e2ac` Textual context before the error. |

## Public attributes

### line

Declared in `unicode/parseerr.h`

```scdoc
int32_t UParseError::line
```
The line on which the error occurred.

If the parser uses this field, it sets it to the line number of the source text line on which the error appears, which will be a value \>= 1. If the parse does not support line numbers, the value will be \<= 0.

### offset

Declared in `unicode/parseerr.h`

```scdoc
int32_t UParseError::offset
```
The character offset to the error.

If the line field is \>= 1, then this is the offset from the start of the line. Otherwise, this is the offset from the start of the text. If the parser does not support this field, it will have a value \< 0.

### postContext

Declared in `unicode/parseerr.h`

```transact-sql
UChar UParseError::postContext[U_PARSE_CONTEXT_LEN]
```
The error itself and/or textual context after the error.

Null-terminated. The empty string if not supported by parser.

### preContext

Declared in `unicode/parseerr.h`

```transact-sql
UChar UParseError::preContext[U_PARSE_CONTEXT_LEN]
```
Textual context before the error.

Null-terminated. The empty string if not supported by parser.