Macro byte_strings::c_str

macro_rules! c_str {
    ($($literal : expr), * $(,) ?) => { ... };
}

Converts into a valid [C string] at compile time (no runtime cost)

This macro takes any number of comma-separated byte string literals, or string literals, and evaluates to (a static reference to) a [C string] made of all the bytes of the given literals concatenated left-to-right, with an appended null byte terminator.

Hence the macro evaluates to the type &'static ::std::ffi::CStr.

Example

use ::byte_strings::c_str;

assert_eq!(
    c_str!("Hello, ", "World!"),
    ::std::ffi::CStr::from_bytes_with_nul(b"Hello, World!\0").unwrap(),
)

Compilation error

For the [C string] to be what should be expected, the arguments cannot contain any null byte. Else the compilation will fail.

Counter example

// error: input literals cannot contain null bytes
let hello_w = c_str!("Hello, ", "W\0rld!");

Macro expansion:

const _: &str = stringify! {
c_str!("Hello, ", "World!")

expands to

unsafe {
    ::std::ffi::CStr::from_bytes_with_nul_unchecked(b"Hello, World!\0")
}