core::assert! 1.0.0
[−]
[src]
macro_rules! assert { ($cond:expr) => { ... }; ($cond:expr, $($arg:tt)+) => { ... }; }
1.0.0
Ensure that a boolean expression is true
at runtime.
This will invoke the panic!
macro if the provided expression cannot be
evaluated to true
at runtime.
Assertions are always checked in both debug and release builds, and cannot
be disabled. See debug_assert!
for assertions that are not enabled in
release builds by default.
Unsafe code relies on assert!
to enforce run-time invariants that, if
violated could lead to unsafety.
Other use-cases of assert!
include
testing and enforcing
run-time invariants in safe code (whose violation cannot result in unsafety).
This macro has a second version, where a custom panic message can be provided.
Examples
fn main() { // the panic message for these assertions is the stringified value of the // expression given. assert!(true); fn some_computation() -> bool { true } // a very simple function assert!(some_computation()); // assert with a custom message let x = true; assert!(x, "x wasn't true!"); let a = 3; let b = 27; assert!(a + b == 30, "a = {}, b = {}", a, b); }// the panic message for these assertions is the stringified value of the // expression given. assert!(true); fn some_computation() -> bool { true } // a very simple function assert!(some_computation()); // assert with a custom message let x = true; assert!(x, "x wasn't true!"); let a = 3; let b = 27; assert!(a + b == 30, "a = {}, b = {}", a, b);