# readInt64

`import { readInt64 } from "destack:bytes";`

Read one signed 64-bit integer.

```ds title="readInt64"
export function readInt64(bytes: &'a readonly [uint8], offset: usize, order?: "bigEndian" | "littleEndian"): int64
```

[language/library/src/bytes/bytes.ds:56:62](https://github.com/destack-sh/destack/blob/main/language/library/src/bytes/bytes.ds#L56-L62)