119 lines
4.6 KiB
Markdown
119 lines
4.6 KiB
Markdown
# String support
|
|
|
|
Burst supports string usage in the following scenarios:
|
|
|
|
* [`Debug.Log`](https://docs.unity3d.com/ScriptReference/Debug.Log.html)
|
|
* Assigning a string to the [`FixedString`](https://docs.unity3d.com/Packages/com.unity.collections@2.2/api/Unity.Collections.FixedString.html) structs that `Unity.Collections` provides, for example [`FixedString128Bytes`](https://docs.unity3d.com/Packages/com.unity.collections@2.2/api/Unity.Collections.FixedString128Bytes.html).
|
|
* The [`System.Runtime.CompilerServices`](https://docs.microsoft.com/en-us/dotnet/api/system.runtime.compilerservices?view=net-6.0) attributes `[CallerLineNumber]`, `[CallerMemberName]`, and `[CallerFilePath]` on arguments to Burst functions. However, you can only pass the strings directly to calls to `Debug.Log`.
|
|
|
|
A string can be either:
|
|
* A string literal. For example: `"This is a string literal"`.
|
|
* An interpolated string using `$"This is an integer {value}` or using `string.Format`, where the string to format is also a string literal.
|
|
|
|
For example, Burst supports the following constructions:
|
|
|
|
* Logging with a string literal:
|
|
|
|
```c#
|
|
Debug.Log("This a string literal");
|
|
```
|
|
|
|
* Logging using string interpolation:
|
|
|
|
```c#
|
|
int value = 256;
|
|
Debug.Log($"This is an integer value {value}");
|
|
```
|
|
|
|
This is the same as using `string.Format` directly:
|
|
|
|
```c#
|
|
int value = 256;
|
|
Debug.Log(string.Format("This is an integer value {0}", value));
|
|
```
|
|
|
|
## Supported `Debug.Log` methods
|
|
|
|
Burst supports the following [`Debug.Log`](https://docs.unity3d.com/ScriptReference/Debug.Log.html) methods:
|
|
|
|
* `Debug.Log(object)`
|
|
* `Debug.LogWarning(object)`
|
|
* `Debug.LogError(object)`
|
|
|
|
## String interpolation support
|
|
|
|
String interpolation has the following restrictions:
|
|
|
|
* The string must be a string literal
|
|
* Burst supports the following `string.Format` methods:
|
|
* `string.Format(string, object)`
|
|
* `string.Format(string, object, object)`
|
|
* `string.Format(string, object, object, object)`
|
|
* `string.Format(string, object[])`. Use this for a string interpolation that contains more than three arguments, for example `$"{arg1} {arg2} {arg3} {arg4} {arg5}"`. In this case, the `object[]` array needs to be a constant size and no arguments should involve control flows (for example, `$"This is a {(cond ? arg1 : arg2)}"`).
|
|
* The string must only use value types
|
|
* The string must take only built-in type arguments:
|
|
* `char`
|
|
* `boolean`
|
|
* `byte` / `sbyte`
|
|
* `double`
|
|
* `float`
|
|
* `short` / `ushort`
|
|
* `int` / `uint`
|
|
* `long` / `ulong`
|
|
* Burst supports all vector types (for example `int2`, `float3`), except `half` vector types. For example:
|
|
|
|
```c#
|
|
var value = new float3(1.0f, 2.0f, 3.0f);
|
|
// Logs "This value float3(1f, 2f, 3f)"
|
|
Debug.Log($"This value `{value}`");
|
|
* Burst doesn't support `ToString()` of structs. It displays the full name of the struct instead.
|
|
|
|
For more information, refer to the .NET documentation on [String interpolation](https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/tokens/interpolated) and [Standard numeric format strings](https://docs.microsoft.com/en-us/dotnet/standard/base-types/standard-numeric-format-strings).
|
|
|
|
## Managed strings
|
|
|
|
You can pass a managed `string` literal or an interpolated string directly to `Debug.Log`, but you can't pass a string to a user method or use them as fields in a struct. To pass around or store strings, use one of the [`FixedString`](https://docs.unity3d.com/Packages/com.unity.collections@1.2/api/Unity.Collections.FixedString.html) structs in the `Unity.Collections` package:
|
|
|
|
```c#
|
|
int value = 256;
|
|
FixedString128 text = $"This is an integer value {value} used with FixedString128";
|
|
MyCustomLog(text);
|
|
|
|
// ...
|
|
|
|
// String can be passed as an argument to a method using a FixedString,
|
|
// but not using directly a managed `string`:
|
|
public static void MyCustomLog(in FixedString128 log)
|
|
{
|
|
Debug.Log(text);
|
|
}
|
|
```
|
|
|
|
## Arguments and specifiers
|
|
|
|
Burst has limited support for string format arguments and specifiers:
|
|
|
|
```c#
|
|
int value = 256;
|
|
|
|
// Padding left: "This value ` 256`
|
|
Debug.Log($"This value `{value,5}`");
|
|
|
|
// Padding right: "This value `256 `
|
|
Debug.Log($"This value `{value,-5}`");
|
|
|
|
// Hexadecimal uppercase: "This value `00FF`
|
|
Debug.Log($"This value `{value:X4}`");
|
|
|
|
// Hexadecimal lowercase: "This value `00ff`
|
|
Debug.Log($"This value `{value:x4}`");
|
|
|
|
// Decimal with leading-zero: "This value `0256`
|
|
Debug.Log($"This value `{value:D4}`");
|
|
```
|
|
|
|
## Additional resources
|
|
|
|
* [HPC# Overview](csharp-hpc-overview.md)
|
|
* [C#/.NET type support](csharp-type-support.md)
|
|
* [C#/.NET System namespace support](csharp-system-support.md) |