How to check if string has at least one letter, number and special character in php

Lowercase character, Uppercase character, Digit, Symbol

^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*(_|[^\w])).+$

A short explanation:

^ // the start of the string
(?=.*[a-z]) // use positive look ahead to see if at least one lower case letter exists
(?=.*[A-Z]) // use positive look ahead to see if at least one upper case letter exists
(?=.*\d) // use positive look ahead to see if at least one digit exists
(?=.*[_\W]) // use positive look ahead to see if at least one underscore or non-word character exists
.+ // gobble up the entire string
$ // the end of the string

Here is more explain of this type of password security in regex

Minimum 8 characters at least 1 Alphabet and 1 Number:

"^(?=.*[A-Za-z])(?=.*\d)[A-Za-z\d]{8,}$"

Minimum 8 characters at least 1 Alphabet, 1 Number and 1 Special Character:

"^(?=.*[A-Za-z])(?=.*\d)(?=.*[$@$!%*#?&])[A-Za-z\d$@$!%*#?&]{8,}$"

Minimum 8 characters at least 1 Uppercase Alphabet, 1 Lowercase Alphabet and 1 Number:

"^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)[a-zA-Z\d]{8,}$"

Minimum 8 characters at least 1 Uppercase Alphabet, 1 Lowercase Alphabet, 1 Number and 1 Special Character:

"^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[$@$!%*?&])[A-Za-z\d$@$!%*?&]{8,}"

Minimum 8 and Maximum 10 characters at least 1 Uppercase Alphabet, 1 Lowercase Alphabet, 1 Number and 1 Special Character:

"^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[$@$!%*?&])[A-Za-z\d$@$!%*?&]{8,10}"

I hope this will help you