php filter_has_var determines whether a variable exists function_PHP tutorial

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Definition and usage
The filter_has_var() function checks if a variable of the specified input type exists.

Returns TRUE or FALSE on success on failure.

Grammar

filter_has_var(type, variable)

type	必需的。指定类型检查可能存在的输入类型： INPUT_GET INPUT_POST INPUT_COOKIE INPUT_SERVER INPUT_ENV
variable	必需的。指定变量检查

• Required. Specify type checking for possible input types: INPUT_GET
• INPUT_POST
• INPUT_COOKIE
• INPUT_SERVER
• INPUT_ENV

variable

Required. Specify variable check

例如
在这个例子中的输入变量“名称”发送到PHP页面：

<!--?phpif(!filter_has_var(INPUT_GET, "name")) { echo("Input type does not exist"); }else { echo("Input type exists"); }?-->

输出为.

 Input type exists

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