Simple Dynamic Strings

Simple Dynamic Strings is a C string library developed to address the limitations of the standard C library’s string handling (null-terminated char pointers) by providing heap-allocated, binary-safe, efficient dynamic strings. The library was originally used internally in Redis, but pulled out as a standalone project to allow any C project to benefit from its features. SDS strings maintain metadata (length, allocation size) just before the pointer returned to the user, while still being compatible with standard C string APIs (null-terminated). They enable common operations like concatenation, formatted append, efficient growth and trimming, and safe binary data handling. The design emphasises simplicity, compatibility, performance and minimal overhead: you still get a C-style char * string pointer, but you also get length tracking, safe memory management, and higher-level string operations. As a mature library, it is used in performance-sensitive contexts.