Running composer with php7.0

Question

I have a server where I have two versions of PHP installed (PHP-7.0 and PHP-7.1). I also have two sites one using magento2.1.5 (running PHP-7.0.18) and the other a Code Ignitor project(running PHP-7.1.6).
We all know magento2.1.5 is not compatible with PHP-7.1.6. I am compiling Magento projects using this and it works fine.
Now I need to use Composer, each time i run composer install it shows the following error:

Problem 1
- magento/composer 1.0.3 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.6) does not satisfy that requirement.
- magento/composer 1.0.3 requires php ~5.5.0|~5.6.0|~7.0.0 -> your PHP version (7.1.6) does not satisfy that requirement.
- Installation request for magento/composer 1.0.3 -> satisfiable by magento/composer[1.0.3].

Any solution would be appreciated...

Answer 1

You can tell composer to ignore the platform requirements by adding the --ignore-platform-reqs parameter in composer install, composer update etc.

Or you can specify the used production version in your projects composer.json with the "platform" parameter:

"config": {
  "platform": {
    "php": "7.0.18"
  }
}

This way you also ensure that composer update only installs packages that are compatible with PHP 7.0

Answer 2

Could you please check in composer.json for below line

"require": {
        "php": "~5.5.0|~5.6.0|~7.0.0"

Change the above line to

"require": {
        "php": "~5.5.0|~5.6.0|~7.0.0|~7.1.0"

Then run the composer install.

I hope it will works... Try it..