php strip everything but numbers and letters from string code example

Example 1: check value contains numbers or letters php

ctype_digit(string text);

Parameter Used:
The ctype_digit() function in PHP accepts only one parameter.

text : Its mandatory parameter which specifies the tested string.

Return Values:
It returns TRUE if all characters of the string are numeric otherwise 
  return FALSE.
  
Input  : '789495001'
Output : TRUE
Explanation : All digits, return True

Input  : 'adc123' or '789.0877'
Output : FALSE
Explanation: String contains number and string or floating point, 
return false.

Example 2: php remove characters not numbers or letters

$res = preg_replace("/[^a-zA-Z0-9\s]/", "", $string);