to_numeric函数_如何使用PHP Is_Numeric（）函数

女爷i 2022-12-06 15:35 146阅读 0赞

to\_numeric函数

The *is\_numeric()* function in the [PHP programming language][] is used to evaluate whether a value is a number or numeric string. Numeric strings contain any number of digits, optional signs such as + or -, an optional decimal, and an optional exponential. Therefore, +234.5e6 is a valid numeric string. [Binary notation][] and hexadecimal notation are not allowed.

[PHP编程语言中][PHP programming language]的*is\_numeric()*函数用于评估值是数字还是数字字符串。 数字字符串包含任意数量的数字，可选符号(例如+或-)，可选十进制和可选指数。 因此，+ 234.5e6是有效的数字字符串。 不允许使用[二进制表示法][Binary notation]和十六进制表示法。

The *is\_numeric()* function can be used within an *if()* statement to treat numbers in one way and non-numbers in another. It returns *true* or *false*.

可以在*if()*语句中使用*is\_numeric()*函数以一种方式处理数字，以另一种方式处理非数字。 它返回*true*或*false* 。

## Is\_Numeric()函数的示例 **(** Examples of the Is\_Numeric() Function **)** ##

For example:

例如：

<?php if (is_numeric(887)) { echo "Yes"; } else { echo "No"; } ?>

Because 887 is a number, this echos *Yes*. However:

因为887是一个数字，所以回显*是* 。 然而：

<?php if (is_numeric("cake")) { echo "Yes"; } else { echo "No"; } ?>

Because cake is not a number, this echos *No*.

因为蛋糕不是数字，所以呼应*No。*

## 类似功能 **(** Similar Functions **)** ##

A similar function, *ctype-digit()*, also checks for numeric characters, but only for digits—no optional signs, decimals, or exponents allowed. Every character in the string text must be a decimal digit for the return to be *true*. Otherwise, the function returns *false*.

类似的函数*ctype-digit()*也会检查数字字符，但仅检查数字-不允许使用可选的符号，小数或指数。 字符串文本中的每个字符都必须为十进制数字，才能返回*true* 。 否则，该函数返回*false* 。

Other similar functions include:

其他类似功能包括：

*  is\_null() – Finds whether a variable is NULL
    
    is\_null()–查找变量是否为NULL
 *  is\_float() – Finds whether the type of a variable is float
    
    is\_float()–查找变量的类型是否为float
 *  is\_int() – Find whether the type of a variable is integer
    
    is\_int()–查找变量的类型是否为整数
 *  is\_string() – Find whether the type of a variable is string
    
    is\_string()–查找变量的类型是否为字符串
 *  [is\_object()][is_object] – Finds whether a variable is an object
    
    [is\_object()][is_object] –查找变量是否为对象
 *  [is\_array()][is_array] – Finds whether a variable is an array
    
    [is\_array()][is_array] –查找变量是否为数组
 *  is\_bool() – Finds out whether a variable is a boolean
    
    is\_bool()–查找变量是否为布尔值

## 关于PHP **(** About PHP **)** ##

PHP is an abbreviation for Hypertext Preprocessor. It is an open-source HTML-friendly scripting language that is [used by website owners][] to write dynamically generated pages. The code is executed on the server and generates HTML, which is then sent to the client. PHP is a popular server-side language that can be deployed on almost every operating system and platform.

PHP是Hypertext Preprocessor的缩写。 它是一种开放源代码HTML友好脚本语言， [网站所有者使用它][used by website owners]来编写动态生成的页面。 该代码在服务器上执行并生成HTML，然后将其发送到客户端。 PHP是一种流行的服务器端语言，几乎可以在所有操作系统和平台上部署。

> 翻译自: [https://www.thoughtco.com/isnumeric-php-function-2694075][https_www.thoughtco.com_isnumeric-php-function-2694075]

to\_numeric函数

[PHP programming language]: https://www.thoughtco.com/learn-php-2693925
[Binary notation]: https://www.thoughtco.com/what-is-binary-2694150
[is_object]: https://php.net/manual/en/function.is-object.php
[is_array]: https://php.net/manual/en/function.is-array.php
[used by website owners]: https://www.thoughtco.com/why-use-php-2694006
[https_www.thoughtco.com_isnumeric-php-function-2694075]: https://www.thoughtco.com/isnumeric-php-function-2694075