How to use regular expression in php to match only ID cards

php’s regular expression that only matches ID cards is “/\b\d{17}[\dX]\b/”. How to use: 1. Define a string variable containing the ID number. "$string", the regular expression is stored in the "$pattern" variable; 2. Use the "preg_match()" function to match the string; 3. Use the "if" statement to check whether the ID number is matched; 4. If an ID number is matched, use the "echo" statement to print the matched ID number.

The operating environment of this article: Windows 10 system, php8.1.3 version, dell g3 computer.

When using regular expressions to match ID number, you can try the following steps to solve the problem:

Determine the format of the ID number: The format of the ID number may vary, It depends on which country or region you are in. In China, ID numbers usually consist of 18 digits, and the last digit may be a number or the letter X (used to represent 10).

Write a regular expression pattern: Based on the format of the ID number, write a regular expression pattern that can match the ID number. For Chinese ID numbers, the regular expression pattern can be: /\b\d{17}[\dX]\b/.

\b means matching word boundaries to ensure that the entire ID number is matched.

\d means match any number.

{17} means that the previous element (\d) is repeated 17 times.

[\dX] means matching any number or letter X.

\b Used to ensure again that the entire ID number is matched.

Using regular expressions in PHP: Suppose you want to match an ID number in a string, you can write the code like this:

$string="这是一个身份证号码：123456789012345678X";
$pattern='/\b\d{17}[\dX]\b/';
if(preg_match($pattern,$string,$matches)){
//进一步处理匹配到的身份证号码
echo"匹配到的身份证号码：".$matches[0];
}else{
echo"未找到匹配的身份证号码";
}

This code is a match using regular expressions Example of ID number. Let me explain the function and steps of this code step by step:

Step 1: Define the string and regular expression pattern

defines a character that contains the ID number String variable $string. The regular expression pattern is stored in the $pattern variable and is used to match ID numbers.

Step 2: Perform regular expression matching

Use the preg_match() function to match strings. This function accepts three parameters: the regular expression pattern, the string to search for, and an optional variable to store the match results.

Step 3: Check whether the ID number is matched

Check whether the ID number is matched through the if statement. If the match is successful, the next step will be processed; otherwise, the code in the else statement will be executed.

Step 4: Process the matched ID number

If the ID number is matched, use the echo statement to print the matched ID number.

Please note that this is just a simple example, and the specific implementation depends on your specific needs and code architecture.

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