Please help.
Composer cannot be installed.

PHP setting error
"The PHP exe file you specified did not run correctly:
C: \ xampp \ php \ php.exe

The php.ini used by your command-line PHP is: C: \ xampp \ php \ php.ini

A setting in your php.ini could be causing the problem: Either the'extension_dir'value is incorrect or the dll does not exist.

Program Output:
PHP Warning: PHP Startup: Unable to load dynamic library'mysql.dll'(tried: C: \ xampp \ php \ ext \ mysql.dll (The specified module cannot be found), C: \ xampp \ php \ ext \ php_mysql.dll.dll (The specified module cannot be found.) in Unknown on line 0 "
It will be displayed.

Because mysql.dll did not exist before, mysql function could not be used and mysqli function was used.

By the way, the environment is
Using XAMPP for Windows 7.2.6,
The version of php is 7.

Can you tell me the solution?

The version of php was 7.
Composer uses the official installer,
Uncheck Developer mode
Settings Check
Because php.exe in xampp was set,
A php setting error occurred when trying to go to the next screen from Setting Check with the default settings.