How do I log errors and warnings into a file?

Question

How do I turn on all error and warnings and log them to a file, but to set up all of that within the script (not changing anything in php.ini)?

I want to define a fi

Answer 1

add this code in .htaccess (as an alternative of php.ini / ini_set function):

php_flag log_errors on 
php_value error_log ./path_to_MY_PHP_ERRORS.log
# php_flag display_errors on 

* as commented: this is for Apache-type servers, and not for Nginx or others.