Question

我想检查字符串的第一个和最后一个元素是否是字母数字字符，并且字符串的大小并不重要。为了检查它我使用一个小脚本：

if(preg_match("/^\w\w$/", $_GET['eq'])){ 
    echo "<h1>true</h1>"; 
}else{ 
    echo "<h1>false</h1>"; 
}

但是如果输入包含超过2个字符，则表示为false。如何查看更大的字符串？在我看来/^\w\w$/应该检查第一个和最后一个字符与字符串的大小无关。

Answer 1

您必须匹配并忽略所有中间字符：/^\w.*\w$/

所以，你的代码必须是：

if(preg_match("/^\w.*\w$/", $_GET['eq'])){ 
    echo "<h1>true</h1>"; 
}else{ 
    echo "<h1>false</h1>"; 
}

Answer 2

例如，您可以使用

^\w.*\w$

.*匹配任何字符（行终止符除外）

Answer 3

尝试以下方法：

if(preg_match("/^[^A-Za-z0-9]+|[^A-Za-z0-9]+$/", $_GET['eq'])){ 
    echo "<h1>true</h1>"; 
}else{ 
    echo "<h1>false</h1>"; 
}

您需要能够跳过中间的所有字符。

Answer 4

你的正则表达式只匹配一个2个字符的字符串。试试这个（.*将允许它在中间可选地扩展）：

if(preg_match("/^\w.*\w$/", $_GET['eq'])){ 
    echo "<h1>true</h1>"; 
}else{ 
    echo "<h1>false</h1>"; 
}

Answer 5

你可以使用它，它会接受任何东西，但第一个和最后一个字符将是字母数字。

if(preg_match('/^[A-Za-z0-9]{1}.*[A-Za-z0-9]{1}?$/i', $_GET['eq'])){ 
    echo "<h1>true</h1>"; 
}else{ 
    echo "<h1>false</h1>"; 
}

表达解释：

^ Beginning. Matches the beginning of the string, or the beginning of a line if the multiline flag (m) is enabled.
[ Character set. Match any character in the set.
A-Z Range. Matches a character in the range "A" to "Z" (char code 65 to 90).
a-z Range. Matches a character in the range "a" to "z" (char code 97 to 122).
0-9 Range. Matches a character in the range "0" to "9" (char code 48 to 57).
]
{1} Quantifier. Match 1 of the preceding token.
. Dot. Matches any character except line breaks.
* Star. Match 0 or more of the preceding token.
[ Character set. Match any character in the set.
A-Z Range. Matches a character in the range "A" to "Z" (char code 65 to 90).
a-z Range. Matches a character in the range "a" to "z" (char code 97 to 122).
0-9 Range. Matches a character in the range "0" to "9" (char code 48 to 57).
]
{1} Quantifier. Match 1 of the preceding token.
? Lazy. Makes the preceding quantifier lazy, causing it to match as few characters as possible.
$ End. Matches the end of the string, or the end of a line if the multiline flag (m) is enabled.

检查字符串的第一个和最后一个元素是否是带有模式的字母数字字符

5 个答案: