# string_width
[](https://hex.pm/packages/string_width)
[](https://hexdocs.pm/string_width/)
```sh
gleam add string_width@2
```
```gleam
import string_width
pub fn main() {
string_width.dimensions("hello,\n안녕하세요", [])
// --> #(2, 10)
string_width.line("👩👩👦👦", [string_width.HandleGraphemeClusters])
// --> 2
}
```
A small package estimating the required number of cells when printing a string on the terminal. It supports all Gleam targets and passes the tests of the NPM [string-width](https://www.npmjs.com/package/string-width) package.
### Limitations
- Many terminals don't support grapheme clusters properly, so by default, the
values returned by this library try to match the behaviour of libc instead
of modern text rendering pipelines.
- The width of many characters is context-dependent and may vary based on the
current locale, selected font, operating system, or surrounding context;
The numbers reported by the functions in this library may not be fully accurate.
If you encounter a mismatch that is consistent across multiple environments,
feel free to open an issue or ping me on Discord!
- The behaviour when encountering stray variant selectors does not match other similar libraries.
### Sources
The table lookup technique used by this library is heavily based on the musl libc `wcwidth` implementation. I built updated tables using the Unicode 16.0 data, and added support for ambiguous characters. It also uses the regex of the ansi-regex npm package, and the test cases of the string-width npm package.
- **UAX #11 East Asian Width:** [https://www.unicode.org/reports/tr11/](https://www.unicode.org/reports/tr11/)
- **Grapheme Clusters in Terminals:** [https://mitchellh.com/writing/grapheme-clusters-in-terminals](https://mitchellh.com/writing/grapheme-clusters-in-terminals)
- **get-east-asian-width:** [https://github.com/sindresorhus/get-east-asian-width](https://github.com/sindresorhus/get-east-asian-width)
- **string-width:** [https://github.com/sindresorhus/string-width](https://github.com/sindresorhus/string-width)
- **ansi-regex:** [https://github.com/chalk/ansi-regex](https://github.com/chalk/ansi-regex)
- **musl-libc wcwidth:** [https://git.musl-libc.org/cgit/musl/tree/src/ctype/wcwidth.c](https://git.musl-libc.org/cgit/musl/tree/src/ctype/wcwidth.c)
- **glibc wcwidth:** [https://sourceware.org/git/?p=glibc.git;a=blob;f=wcsmbs/wcwidth.h;hb=HEAD](https://sourceware.org/git/?p=glibc.git;a=blob;f=wcsmbs/wcwidth.h;hb=HEAD)
