PHP中的正则布尔函数_Php_Regex

PHP中的正则布尔函数

php regex

PHP中的正则布尔函数,php,regex,Php,Regex,我有一个字符串，我想测试它是否符合以下格式 exactly seven alphabetical OR numerical characters, followed by a '_', followed by exactly five alphabetical OR numerical characters, followed by a '_', followed by exactly seven alphabetical OR numerical characters, followed

我有一个字符串，我想测试它是否符合以下格式

exactly seven alphabetical OR numerical characters, followed by a '_', followed by 
exactly five alphabetical OR numerical characters, followed by a '_', followed by 
exactly seven alphabetical OR numerical characters, followed by a '_', followed by 
exactly nine alphabetical OR numerical characters. 
No other characters should exist other then the above mentioned characters.

我想要一个函数，如果与描述匹配，则返回true；如果不匹配，则返回false

编辑：字母和数字字符可以混合使用。

与此匹配的正则表达式为：

^[a-zA-Z0-9]{7}_[a-zA-Z0-9]{5}_[a-zA-Z0-9]{7}_[a-zA-Z0-9]{9}$

语法的简要概述：

```
^
```
只匹配字符串的开头<代码>$仅与结尾匹配
```
[
```
和
```
]
```
表示要匹配的字符。它们可以包括像
```
0-9
```
这样的范围
```
{
```
和
```
}
```
表示前一件事重复特定次数

{}

[]

preg_match('/^[a-z0-9]{7}_[a-z0-9]{5}_[a-z0-9]{7}_[a-z0-9]{9}$/i', $str);