# Unsigned char std::basic\_string\<\> in C++

DevFeed: [Unsigned char std::basic\_string\<\> in C++](<https://devfeed.tech/articles/unsigned-char-std-basic-string-in-c-36572.md>)

Original publisher: [Read original article](<https://berthub.eu/articles/posts/unsigned-char-std-string-cpp/>)

Published: 2026-01-03T22:00:02Z

Content type: tutorial

Language: en

Sources: [Bert Hubert's writings](<https://devfeed.tech/sources/bert-hubert-s-writings.md>)

Topics: [C++](<https://devfeed.tech/topics/c-plus-plus.md>), [standard](<https://devfeed.tech/topics/standard.md>), [LLVM](<https://devfeed.tech/topics/llvm.md>), [clang](<https://devfeed.tech/topics/clang.md>), [gcc](<https://devfeed.tech/topics/gcc.md>)

Tags: [bits](<https://devfeed.tech/tags/bits.md>), [c-plus-plus](<https://devfeed.tech/tags/c-plus-plus.md>), [clang](<https://devfeed.tech/tags/clang.md>), [concatenation](<https://devfeed.tech/tags/concatenation.md>), [cryptographic](<https://devfeed.tech/tags/cryptographic.md>), [freebsd](<https://devfeed.tech/tags/freebsd.md>), [gcc](<https://devfeed.tech/tags/gcc.md>), [llvm](<https://devfeed.tech/tags/llvm.md>), [openbsd](<https://devfeed.tech/tags/openbsd.md>), [standard](<https://devfeed.tech/tags/standard.md>), [string](<https://devfeed.tech/tags/string.md>)

## AI overview

A C++ post explains why code using std::basic_string<uint8_t> can fail on FreeBSD and OpenBSD. The issue involves std::char_traits: LLVM 19 removed its unconstrained base template because the C++ Standard does not require it for unsigned-character types. Code may need string concatenation and related operations replaced or a correct custom specialization provided.

## Source excerpt

Brief post on a somewhat vexing and irritating C++ problem I ran into some time ago. I hope that this page will help other people deal with this problem more quickly than I did. I've long used std::basic_string<uint8_t>, an unsigned char string, for fiddling with bits. You could use a regular char string, but especially when doing cryptographic or sub-byte operations, it is more convenient to not have to deal with sign bits.