Struct CStrStack 

pub struct CStrStack<const N: usize> { /* private fields */ }

A stack-allocated, null-terminated C string with fixed capacity.

CStrStack<N> stores a formatted string directly on the stack, avoiding heap allocation. The internal buffer has N bytes and is always null-terminated (\0), making it safe to pass to C functions via as_ptr().

Examples

use std::ffi::CStr;
use stack_cstr::{CStrStack, CStrLike};

// Create a stack-allocated C string with capacity for 32 bytes
let s = CStrStack::<32>::new(format_args!("Hello {}", 123)).unwrap();

let cstr: &CStr = s.as_cstr();
assert_eq!(cstr.to_str().unwrap(), "Hello 123");

unsafe {
    // FFI-safe pointer
    assert_eq!(CStr::from_ptr(s.as_ptr()).to_str().unwrap(), "Hello 123");
}

Errors

• Returns Err("buffer overflow") if the formatted string (plus NUL) does not fit in the buffer.
• Returns Err("format failed") if formatting fails (rare case; ArrayString rarely errors).

Implementations

impl<const N: usize> CStrStack<N>

pub fn new(fmt: Arguments<'_>) -> Result<CStrStack<N>, CStrError>

Creates a new stack-allocated C string using a format_args! expression.

The string is written into an internal buffer of size N. If the string does not fit, returns an error.

pub fn as_ptr(&self) -> *const c_char

Returns a raw pointer to the null-terminated C string.

This pointer is valid for as long as self is alive. Suitable for passing to FFI.

pub fn as_cstr(&self) -> &CStr

Returns a reference to the underlying CStr.

Safety

The buffer is guaranteed to be null-terminated by construction, so this is always safe.

Trait Implementations

impl<const N: usize> CStrLike for CStrStack<N>

fn as_ptr(&self) -> *const c_char

Returns a raw pointer to the null-terminated C string.

fn as_cstr(&self) -> &CStr

Returns a reference to the underlying CStr.