# scanDouble(_:) Scans for a double value, returning a found value by reference. ``` func scanDouble(_ result: UnsafeMutablePointer?) -> Bool ``` ## Parameters `result` Upon return, contains the scanned value. Contains `HUGE_VAL` or `–HUGE_VAL` on overflow, or `0.0` on underflow. ## Return Value if the receiver finds a valid floating-point representation, otherwise . Overflow or underflow are both considered valid floating-point representations. ## Discussion Skips past excess digits in the case of overflow, so the scanner’s position is past the entire floating-point representation. Invoke this method with `NULL` as `doubleValue` to simply scan past a double value representation. Floating-point representations are assumed to be IEEE compliant. ## See Also [`doubleValue`](/documentation/Foundation/NSString/doubleValue) The floating-point value of the string as a `double`. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)