What is the best way to validate user input in PHP, specifically when checking for a specific string followed by a variable number?

When validating user input in PHP to check for a specific string followed by a variable number, you can use regular expressions. Regular expressions allow you to define a pattern that the input must match. In this case, you can define a pattern that includes the specific string followed by a variable number of characters. 

$input = "specific_string123";
$pattern = "/specific_string\d+/";

if (preg_match($pattern, $input)) {
    echo "Input is valid!";
} else {
    echo "Input is not valid.";
}

Keywords

PHP user input validation string variable number

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