PHP preg_match-仅允许字母数字字符串和-_个字符 [英] PHP preg_match - only allow alphanumeric strings and - _ characters

问题描述

我需要使用正则表达式来检查字符串是否仅包含数字，字母，连字符或下划线

I need the regex to check if a string only contains numbers, letters, hyphens or underscore

$string1 = "This is a string*";
$string2 = "this_is-a-string";

if(preg_match('******', $string1){
   echo "String 1 not acceptable acceptable";
   // String2 acceptable
}

推荐答案

代码:

if(preg_match('/[^a-z_\-0-9]/i', $string))
{
  echo "not valid string";
}

说明:

• [] =>字符类定义
• ^ =>否定课程
• a-z =>从'a'到'z'的字符
• _ =>下划线
• -=>连字符'-'(您需要对其进行转义)
• 0-9 =>数字(从零到九)

如果您不输入正则表达式末尾的"i"修饰符，则表示不区分大小写"，您需要在执行A-Z之前在代码中添加大写字母

The 'i' modifier at the end of the regex is for 'case-insensitive' if you don't put that you will need to add the upper case characters in the code before by doing A-Z

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