看到这个问题,一开始想应该很简单吧~而且方法还不止一种.
网上查了下,绝大部分的人是使用is_numeric方法,而且后面还经常会跟着一句话,不要把问题想太复杂,巴拉巴拉的...
自己做了下测试,确实不一定正确,is_numeric在手册上的说法是:检测变量是否为数字或数字字符串,数字字符串.
$a = "000022153.26";echo is_numeric($a) ? "Y" : "N";
结果显示的是Y
显然这不是我想要的答案,根据网上有些人的提示,我想到了另一个方法,既然is_numeric是数字或者数字字符串,那先把字符串给排除了不就行了
if (! is_string ( $a )) { if (is_numeric ( $a )) { echo "Y"; exit (); }}echo "N";
得到的结果是正确的,N 再后来看到一个人提示,使用is_nan,我试了下,最后屏幕打印了N,我开始还挺兴奋,以为对了,直接发文章了,其实是错误的,它还是把$a当float来解析了,is_nan 在手册中的意思是判定某个数字是否为非数值,就是NAN, not a number,当$a为一个string类型的字符串,如”a“时,就会直接报错,故使用is_nan是没法实现判断一个变量是否是字符串
echo is_nan($a) ? "Y" : "N"
而在阅读了手册后,找到了最容易找到的方法
$a="0002133.226";if(is_int($a) || is_float($a)){ echo "Y"; }else{ echo "N";}
与之对应的 gettype($a) 然后跟 ”integer“和”double“进行比较,若匹配了就是数字,不过这个的效率没有上面的高,因为它进行了字符串的比较,它是比较慢的
对于刚之前看文章的人如果有误导,非常抱歉了
不积跬步无以至千里

PHP is a server-side scripting language used for dynamic web development and server-side applications. 1.PHP is an interpreted language that does not require compilation and is suitable for rapid development. 2. PHP code is embedded in HTML, making it easy to develop web pages. 3. PHP processes server-side logic, generates HTML output, and supports user interaction and data processing. 4. PHP can interact with the database, process form submission, and execute server-side tasks.

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PHP is used to build dynamic websites, and its core functions include: 1. Generate dynamic content and generate web pages in real time by connecting with the database; 2. Process user interaction and form submissions, verify inputs and respond to operations; 3. Manage sessions and user authentication to provide a personalized experience; 4. Optimize performance and follow best practices to improve website efficiency and security.

PHP uses MySQLi and PDO extensions to interact in database operations and server-side logic processing, and processes server-side logic through functions such as session management. 1) Use MySQLi or PDO to connect to the database and execute SQL queries. 2) Handle HTTP requests and user status through session management and other functions. 3) Use transactions to ensure the atomicity of database operations. 4) Prevent SQL injection, use exception handling and closing connections for debugging. 5) Optimize performance through indexing and cache, write highly readable code and perform error handling.

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