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Steel · hard

62. Steel: Zero-Copy Loading (as_account & as_account_mut)

In-place account reading and writing.

1 min read2 questionsup to 50 XPtopic 62/100

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Steel reads and modifies account data in-place using `as_account::<T>()` and `as_account_mut::<T>()`, avoiding any deserialization copies.

rust
let user = user_info.as_account_mut::<UserState>(&program_id)?;
user.balance += amount;

How to study this topic

  1. 1. Read the explanation once end to end, skipping the code.
  2. 2. Re-read the code snippets and say out loud what each line does.
  3. 3. Answer the quiz without scrolling back — that is the real check.
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Check your understanding

  1. 1. What does as_account_mut::<T>(&program_id) do in Steel?

  2. 2. Does as_account allocate memory on the SBF heap?

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