注意：使用未定义的常量CURL_IPRESOLVE - 假设为'CURL_IPRESOLVE'

I have 2 IP address on my dedicated server

1. ipv4
2. ipv6

i m trying to use ipv6 on CURL, below are code using on curl.

curl_setopt($ch, CURL_IPRESOLVE, CURL_IPRESOLVE_V4);

or

  curl_setopt($ch, CURL_IPRESOLVE_V4, true); 

but i got below error

Notice: Use of undefined constant CURL_IPRESOLVE - assumed 'CURL_IPRESOLVE' in /home/admin....... line 14