php与c++；hmac不一致

我正在尝试集成一个游戏引擎（c++）和一个服务器（php）

c++

php

问题是我的哈希值不匹配，我不确定我做错了什么

char key[] = "012345678";

// The data that we're going to hash using HMAC
char hashStr[] = "hello world";

unsigned char* result = HMAC(EVP_sha256(), key, strlen(key) , (unsigned char*)hashStr, strlen(hashStr), NULL, NULL);  

$key = "012345678";
$msg = "hello world";


$hash = hash_hmac ( 'sha256' , $msg ,  $key , true );

echo(bin2hex($hash));