# withCString(_:) Calls the given closure with a pointer to the contents of the string, represented as a null-terminated sequence of UTF-8 code units. ``` func withCString(_ body: (UnsafePointer) throws -> Result) rethrows -> Result ``` ## Parameters `body` A closure with a pointer parameter that points to a null-terminated sequence of UTF-8 code units. If `body` has a return value, that value is also used as the return value for the `withCString(_:)` method. The pointer argument is valid only for the duration of the method’s execution. ## Return Value The return value, if any, of the `body` closure parameter. ## Discussion The pointer passed as an argument to `body` is valid only during the execution of `withCString(_:)`. Do not store or return the pointer for later use. --- 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)