我在哪里可以下载php扩展

I am a beginner for php. And now I need to get some php extension as below.

[ERROR] bcmath: Extension bcmath does not exist.
[ERROR] bz2: Extension bz2 does not exist.
[ERROR] curl: Extension curl does not exist.
...

for java jar, I know we can get it from maven repository or *www.java2s.com *. But how to do about php extension. And I know I can get extension(xx.so) through phpize command when we have source code of it. But now I dont have anything. what I should do? just search bcmath.so in google? Are there exist some easy way?

PHP extensions are typically installed via whatever package manager your OS uses. For example, on Debian-based Linux distributions, you'd likely use:

apt-get install php-bcmath php-bz2 php-curl

If you're compiling PHP yourself, you'll need to include those extensions via the configure script before you build:

configure --enable-bcmath --with-bz2 --with-curl