--- title: FFI: How Ruby Talks to C | daily.dev description: Ruby can interoperate with C through two main approaches: the FFI gem and C extensions. The FFI gem lets you bind and call existing C library functions from... canonical: https://daily.dev/posts/ffi-how-ruby-talks-to-c-ziuiprg0q twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: FFI: How Ruby Talks to C | daily.dev og:description: Ruby can interoperate with C through two main approaches: the FFI gem and C extensions. The FFI gem lets you bind and call existing C library functions from... og:url: https://daily.dev/posts/ffi-how-ruby-talks-to-c-ziuiprg0q og:image: https://api.daily.dev/og/posts/ZIUIprG0Q.png og:image:alt: FFI: How Ruby Talks to C og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # FFI: How Ruby Talks to C **[Ruby Flow](https://daily.dev/sources/rubyflow)** · 6 min read · 0 upvotes · 0 comments ## Summary Ruby can interoperate with C through two main approaches: the FFI gem and C extensions. The FFI gem lets you bind and call existing C library functions from pure Ruby using a DSL, works across MRI, JRuby, and TruffleRuby, and is naturally compatible with Ruby 3 Ractors for true parallelism. C extensions go deeper — you write C code that integrates with the Ruby runtime via the Ruby C API, allowing C structs to become native Ruby objects with GC integration and zero call overhead, but only on MRI. The post covers installation, type mappings, struct handling, callbacks, Ractor usage with FFI, and the TypedData_Wrap_Struct pattern for C extensions, concluding with a practical decision guide for choosing between the two approaches. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Ruby as an Orchestrator Language](https://daily.dev/posts/ruby-as-an-orchestrator-language-weqg1hher) · Ruby Flow · 1 upvotes · 0 comments - [TruffleRuby](https://daily.dev/posts/truffleruby-zlp4xgkwa) · Hacker News · 0 upvotes · 0 comments - [Going beyond Ruby: Writing a simple C extension](https://daily.dev/posts/going-beyond-ruby-writing-a-simple-c-extension-wpjhkpncz) · RUBYLAND · 0 upvotes · 0 comments - [MRI Internals: How Ruby Arrays Became a VM Playground](https://daily.dev/posts/mri-internals-how-ruby-arrays-became-a-vm-playground-nzklaeapx) · RUBYLAND · 0 upvotes · 0 comments --- Tags: [#c](https://daily.dev/tags/c), [#ruby](https://daily.dev/tags/ruby) [View this post on daily.dev](https://daily.dev/posts/ffi-how-ruby-talks-to-c-ziuiprg0q) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"FFI: How Ruby Talks to C","url":"https://daily.dev/posts/ffi-how-ruby-talks-to-c-ziuiprg0q","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/ffi-how-ruby-talks-to-c-ziuiprg0q"},"datePublished":"2026-03-26T07:48:20.499Z","dateModified":"2026-03-26T07:49:02.604Z","description":"Ruby can interoperate with C through two main approaches: the FFI gem and C extensions. 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