Composer install error - requires ext_curl when it's actually enabled

I'm trying to install Facebook PHP SDK with Composer. This is what I get

$ composer install
Loading composer repositories with package information
Installing dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

    Problem 1
        - Installation request for facebook/php-sdk dev-master -> satisfiable by facebook/php-sdk[dev-master].
        - facebook/php-sdk dev-master requires ext-curl * -> the requested PHP extension curl is missing from your system.

Problem is, I have curl extension enabled (uncommented in php.ini). When I run phpinfo(), it says it's enabled. Only clue I have is that when I run $ php -m, 'curl' line is missing but I don't know what to do about it.

I have wamp 2.4 on Win8 and I'm running composer in cmd.exe.

This is caused because you don't have a library php5-curl installed in your system,

On Ubuntu its just simple run the line code below, in your case on Xamp take a look in Xamp documentation

sudo apt-get install php5-curl

For anyone who uses php7.0

sudo apt-get install php7.0-curl

For those who uses php7.1

sudo apt-get install php7.1-curl

For those who use php7.2

sudo apt-get install php7.2-curl

For those who use php7.3

sudo apt-get install php7.3-curl

For those who use php7.4

sudo apt-get install php7.4-curl

For those who use php8.0

sudo apt-get install php8.0-curl

Or simply run below command to install by your version:

sudo apt-get install php-curl

This worked for me: http://ubuntuforums.org/showthread.php?t=1519176

After installing composer using the command curl -sS https://getcomposer.org/installer | php just run a sudo apt-get update then reinstall curl with sudo apt-get install php5-curl. Then composer's installation process should work so you can finally run php composer.phar install to get the dependencies listed in your composer.json file.

on php7 run for example:

> sudo apt-get install php-curl
> sudo apt-get install php-mbstring

for every missing extension. Then:

> sudo apt-get update

and finally (in the project's root folder):

> composer install

As Danack said in comments, there are 2 php.ini files. I uncommented the line with curl extension in the one in Apache folder, which is php.ini used by the web server.

Composer, on the other hand, uses php for console which is a whole different story. Php.ini file for that program is not the one in Apache folder but it's in the PHP folder and I had to uncomment the line in it too. Then I ran the installation again and it was OK.

I ran into the same issue trying to install Dropbox SDK.

CURL was indeed enabled on my system but this meant by the php.ini in the wamp\bin\apache folder.

I simply had to manually edit the php.ini situated in wamp\bin\php, uncomment the extension=php_curl.dll line, restart Wamp and it worked perfectly.

Why there are those 2 php.ini and only one is used is still a mystery for me...

Hope it's helpul to someone!