tjol/sprintf-rs

a clone of C s(n)printf in Rust

sprintf-rs

a clone of C sprintf in Rust

This crate was created out of a desire to provide C printf-style formatting in a WASM program, where there is no libc.

Note: You're probably better off using standard Rust string formatting instead of this crate unless you specificaly need printf compatibility.

This crate implements a dynamically type-checked function vsprintf and macro sprintf!.

Usage example:

use sprintf::sprintf;
let s = sprintf!("%d + %d = %d\n", 3, 9, 3+9).unwrap();
assert_eq!(s, "3 + 9 = 12\n");

libc is a dev dependency as it is used in the tests to compare results. std is used for some maths functions.

sprintf-rs's Issues

"%.1f" of 999.99 => "999.0"

Incorrect rounding of floating point numbers:

sprintf!("%.1f",999.99).unwrap() == "999.0"

should be "1000.0"

Print pointer addresses

I'm converting a printf-like call from C to rust that uses %p to print the address of a pointer but currently pointers are not supported in this library.

The p conversion type is parsed and the address of a pointer is safe data so it should be fine to accept a pointer.
Is this the case? I can make a PR.

Alternatively maybe you want users to require an explicit cast to usize (or .addr() with strict_provenance).
Is this the case? If so, the docs should be updated to reflect that.

Support C string types

I tried to use this crate with C string pointers but failed.

Are you ok with implementing sprintf::Printf for:

• std::ffi::CStr
• std::ffi::CString
• *const c_char
• *mut c_char
• c_char too if possible

I don't mind having to enable a feature flag.