From 728311643d4bb2cbe2d430070268b52ca2e66d85 Mon Sep 17 00:00:00 2001
From: mqy <meng.qingyou@gmail.com>
Date: Fri, 25 Feb 2022 12:29:47 +0800
Subject: [PATCH] ffi: explicitly declare hello_from_rust for C99

---
 src/ffi.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/ffi.md b/src/ffi.md
index 9e02eee8..45a1f61e 100644
--- a/src/ffi.md
+++ b/src/ffi.md
@@ -281,6 +281,8 @@ We'll create a C file to call the `hello_from_rust` function and compile it by `
 C file should look like:
 
 ```c
+extern void hello_from_rust();
+
 int main(void) {
     hello_from_rust();
     return 0;