PHP regular expression to verify whether the input string is the correct QQ number format

PHP regular expression to verify whether the input string is the correct QQ number format

QQ number is the unique identifier of the user of QQ, the largest instant messaging software in China, and its format is 5~11 digits. In order to ensure the accuracy of the entered QQ number, developers often need to verify the QQ number entered by the user. At this time, PHP regular expressions can come in handy.

First of all, we need to understand the syntax of regular expressions. Only by understanding the syntax of regular expressions can we write the correct regular expression to verify the format of the QQ number.

Regular expression is a general text matching pattern, through which complex search and replacement operations can be performed on strings. Regular expressions consist of special symbols and characters that form a rule and are used to identify and match text that conforms to the rule.

The following is a simple PHP regular expression used to match the QQ number format:

$preg = '/^[1-9]d{4,10}$/';

Explain this regular expression:

• ^ represents a string beginning.
• [1-9] means the first number must be a number between 1 and 9.
• d represents any number. And {d4,10} means matching any five to ten consecutive numbers.
• $ represents the end of the string.

According to the above regular rules, we can use PHP code to verify whether the string is in the correct QQ number format:

function is_qq_number($string)
{
    $preg = '/^[1-9]d{4,10}$/';
    return preg_match($preg, $string) ? true : false;
}

The preg_match function here is used to execute the regular expression match. When the match is successful, 1 is returned, and when the match fails, 0 is returned. Therefore, when the match is successful, we can be sure that the input string matches the format of the QQ number.

The following is a complete example to demonstrate how to verify whether the input string is in the correct QQ number format:

function is_qq_number($string)
{
    $preg = '/^[1-9]d{4,10}$/';
    return preg_match($preg, $string) ? true : false;
}

$input_str = '12345678';
if(is_qq_number($input_str)){
    echo '输入字符串'.$input_str.'是一个正确的QQ号码格式';
}else{
    echo '输入字符串'.$input_str.'不是一个正确的QQ号码格式';
}

When the value of $input_str is 12345678, because this is a correct QQ number format, so the output result of the program will be "The input string 12345678 is a correct QQ number format."

The above code passes the input string as a parameter to the is_qq_number function. If true is returned, it means that the input string conforms to the QQ number format, otherwise it does not. We can use this method to verify whether the QQ number entered by the user is in the correct format.

As we can see, it is very simple to use regular expressions to verify that the input string is in the correct QQ number format. Once you know the syntax of regular expressions, you can easily implement the string verification function with just a few lines of code. At the same time, this method is also suitable for other scenarios where string format verification is required.

The above is the detailed content of PHP regular expression to verify whether the input string is the correct QQ number format. For more information, please follow other related articles on the PHP Chinese website!