Adding `microstr` library as a dependency

Run this command in a terminal, in your project's directory:

cargo add microstr

To add it manually, edit your project's Cargo.toml file and add to the [dependencies] section:

microstr = "0.4.0"

The microstr library will be automatically available globally. Read the microstr library documentation.

Back to the crate overview.

Readme

MicroStr

A lightweight, stack-allocated string with fixed capacity and UTF-8 support.
Ideal for no_std environments, embedded systems, and performance-critical code.

[dependencies]
microstr = "0.4"

What is MicroStr?

✅ No heap allocations — fully stack-based.
✅ UTF-8 safe — always valid string content.
✅ no_std by default — works without std.
✅ Const generic capacity — size known at compile time.
✅ Truncation-aware — safely appends strings without overflow.
✅ Seamless std integration — supports Display, Debug, From<String>, etc.
✅ Optional serde support — JSON (de)serialization with length checking.

Usage

use microstr::MicroStr;

// Create a string with capacity of 16 bytes
let mut s: MicroStr<16> = MicroStr::new();

s.push_str("Hello");
s.push('!');

assert_eq!(s.as_str(), "Hello!");
assert_eq!(s.len(), 6);           // 6 Unicode chars
assert_eq!(s.bytes_len(), 6);     // 6 bytes
assert_eq!(s.push_str(" this won't fit entirely"), Err(10)); // Truncated safely

You can also use it like a regular &str thanks to Deref:

if s.starts_with("Hello") {
    println!("Greeting: {}", s);
}

Cargo Features

Enable optional features in Cargo.toml:

[dependencies]
microstr = { version = "0.4", features = ["std", "serde"] }

Feature	Description
`std` (default: on)	Enables `Display`, `Debug`, `From<String>`, and `ToString`.

Why MicroStr?

Predictable performance: No allocations, no heap usage.
Memory safety: Always valid UTF-8, no buffer overflows.
Great for constrained environments: Embedded, kernels, WASM.
Easy migration: Drop-in replacement for String in many cases.
Macro: Creation via the convenient macro microstr!

Comparison with `heapless::String`

Feature	`microstr`	`heapless::String`
UTF-8 safety	✅ Always valid	✅ Always valid
`no_std`	✅ Yes	✅ Yes
Truncation on write	✅ Yes (safe)	❌ Returns `Err` on overflow
`const fn` support	✅ `from_const`, `new`	Limited
Macro convenience	✅ `microstr!`	❌ No built-in macro

microstr prioritizes zero-cost truncation and ease of use in embedded contexts.

API Documentation

📚 Full documentation: https://docs.rs/microstr

License

MIT License

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you shall be dual licensed as above, without any additional terms or conditions.

Adding microstr library as a dependency

Adding `microstr` library as a dependency