Checking if a string contains a character could be accomplished easily with a
regular expression or you can use the built-in PHP functions.
To check if a string contains a character of a specific case you can use
strpos.
$haystack = 'This is my haystack that we shall check'
$has_A = strpos($haystack, 'A') !== false
$has_a = strpos($haystack, 'a') !== false
And if you happen to not care about the character’s case, you can use stripos.
$has_a = stripos($haystack, 'a') !== false
The strpos functions return the numeric position of the character. If it
can’t find the character, it will return a boolean false (hence the ===).
These functions can also work with strings of two or more character and not
limited to just a single character at a time.
