# actix_web::http::header::EXPECT - Rust
API documentation for the Rust `EXPECT` constant in crate `actix_web`.
Keywords: rust, rustlang, rust-lang, EXPECT

# [−] [src] Constant actix_web::http::header::EXPECT

    pub const EXPECT: HeaderName

Indicates expectations that need to be fulfilled by the server in order to properly handle the request.

The only expectation defined in the specification is Expect: 100-continue, to which the server shall respond with:

- 100 if the information contained in the header is sufficient to cause an immediate success,

- 417 (Expectation Failed) if it cannot meet the expectation; or any other 4xx status otherwise.

For example, the server may reject a request if its Content-Length is too large.

No common browsers send the Expect header, but some other clients such as cURL do so by default.

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g. `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g. `vec -> usize` or `* -> vec`)

Search multiple things at once by splitting your query with comma (e.g. `str,u8` or `String,struct:Vec,test`)