How to remove non-Chinese characters, non-letters, and non-numeric characters from a string

How do I remove non-Chinese characters, non-letters, and non-numeric characters from a string? How to remove all references of non-Chinese characters, non-letters, non-numbers, and uncommon punctuation marks (commas, periods, and backslash) in a string, such as: 4/13 characters (& amp; #9728;, Middle... 3 ???...? Iii) & nbsp ;?? Love me Chinese = & How does nbs remove non-Chinese characters, non-letters, and non-numeric characters in strings?
How to remove all characters including non-Chinese characters, non-letters, non-numbers, and uncommon punctuation marks (commas, periods, and backslash) in a string

Reference

For example, 4/13 million RMB (☀, Category... 3 ???...? Iii )?? Love me China = promote my country Wei [turn]

After filtering: 4/13 troubles 9728 love me China Yang our country

------ Solution --------------------
Do you mean only numbers and English letters?
Preg_match ("/^ [a-z0-9] + [^ _] $/g", $ a); did not test handwriting. read the class library by yourself