Format Strings
Format Strings
In some applications, Roblox uses locale-aware format strings as patterns for string matching and reformatting. For instance, format strings can be used with LocalizationService automatic text replacement and the Translator APIs.
Parameters
Parameters in format strings are denoted with curly braces like {1}. Parameters must be explicitly numbered or named for recognition.
Remember these rules when using parameters in format strings:
- Numbered parameters use 1-based indexing like
{1},{2}, etc. - Named parameters look like
{user}or{item}. - Named and numbered parameters cannot be mixed in the same format string!
- The empty string indicator
{}can be used to represent an empty string, but there must be no characters before or after the brackets (otherwise it will be invalid). - Curly braces in text must be escaped like
{{or}}.
Format Specifiers
Format specifiers are used to control how a parameter value is formatted. They can be used for locale-aware numbers, dates, and time formatting.
Format specifiers can be noted after the parameter name/index, separated by :, for instance:
{1:int}{2:fixed}{gametime:shorttime}
| Specifier | Type | Description | Example Output |
|---|---|---|---|
| int | number | Integer with optional negative sign; no thousand separators. | 1234 |
| fixed | number | Two decimals with decimal indicator, optional negative sign, and no thousand separators. | 1234.50 |
| num | number | Two decimals with decimal indicator, optional negative sign, and thousand separators. | 1,234.50 1 234,50 |
| HEX | number | Integer converted to hex; negative is converted to 64-bit two's complement. | 3FF |
| hex | number | Same as HEX, but lowercase. | 3ff |
| datetime | number | UTC timestamp as a number to universal user-readable format. | 2017-10-10 13:38:10 |
| iso8601 | number | UTC timestamp as a number to ISO-8601 format UTC time. | 2017-10-12T22:02:38Z |
| shorttime | number | UTC timestamp to local "hour:minute" format. | 1:45 PM 13:45 |
| shortdatetime | number | UTC timestamp to general date+time pattern with short time. | 10/10/2017 1:45 PM |
| shortdate | number | UTC timestamp to short date pattern. | 10/10/2017 2017-10-10 |
| translate | string | Attempts to translate the argument before concatenating (in the same context). This will only look for a literal Source match — it does not support recursive matching. | |
| (nothing) | string | Inserts string. | |
| (nothing) | number | int if integral; fixed if not. |
translate, will greedily match any substring, similar to the Lua .* Articles/string patterns reference|string pattern. The other specifiers are more strict.
Localization Matches
Format strings are often used in Articles/Roblox Localization Tools|game localization. In this application, if a LocalizationTable entry contains a non-empty format string within Source, it will be used for matching.
Consider these example translations from a CSV import file:
| D | E | F |
| Source | es-es | |
| ${1} Cash | ${1} Efectivo | |
| Hello {user}! | Hola {user}! |
If this is properly imported into LocalizationService and you have a GUI TextLabel that reads “$1000 Cash,” auto-localization will make it render as “$1000 Efectivo” for Spanish players.
Additionally, Translator/Translate|Translator:Translate() can be used to return a translated string, for example: