# std::option_env!1.0.0 [−] [src]

    macro_rules! option_env {
        ($name:expr) => { ... };
    }

1.0.0

Optionally inspect an environment variable at compile time.

If the named environment variable is present at compile time, this will expand into an expression of type `Option<&'static str>` whose value is `Some` of the value of the environment variable. If the environment variable is not present, then this will expand to `None`.

A compile time error is never emitted when using this macro regardless of whether the environment variable is present or not.

# Examples

fn main() { let key: Option<&'static str> = option_env!("SECRET_KEY"); println!("the secret key might be: {:?}", key); }

    let key: Option<&'static str> = option_env!("SECRET_KEY");
    println!("the secret key might be: {:?}", key);

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