PHP function variable number of parameters function

Introduction to php variable number parameter function

Using default parameters is suitable for situations where the number of actual parameters is less than the formal parameters, while the variable parameter list is Suitable for situations where there are more actual parameters than formal parameters. It is meaningless if the parameters passed in are not used in the function.

In the previous section we introduced php default parameter function, this section will introduce the function of php variable number of parameters.

Function with variable parametersThe format description is as follows:

mixed funName (string arg1 [, string ...] )    //在参数列表中出现使用  ...  描述的参数

Usually, when users define a function, the number of parameters set is limited. If you want the function to accept any number of parameters, you need to use the func_get_args() function provided by the PHP system in the function, which returns all parameters passed to the script function as an array.

Declare a function that prints the value of the parameter list. Although there is no parameter list declared, any number and type of parameter values ​​can be passed in. First return all the parameters passed to the script function as an array, then use a for loop to traverse the array, output each parameter passed to the function respectively, and finally call this function and input multiple parameters.

The example code is as follows:

<?php
 function more_args(){
   $args = func_get_args();      //将所有传递给脚本的参数当做一个数组返回
   for($i = 0; $i < count($args); $i++){          //使用for循环
     echo "第".$i."个参数：".$args[$i]."<br>";    //分别输出传入函数的每个参数
   }
 }
 more_args(1, 2, 3);       //调用函数并输入多个参数
?>

The output result is as follows:

The 0th parameter: 1

1st parameter: 2

2nd parameter: 3

In addition, you can also use func_num_args () function returns the total number of parameters. Use the func_get_args() function to accept a numeric parameter and return the specified parameter. Here we need to delete all the parameters passed to the script in the previous example as $args returned as an array, then use the func_num_args() function to calculate the total number of parameters, and then use func_get_arg to loop out each parameter passed into the function . Finally call this function and enter multiple parameters.

The modified example code is as follows:

<?php
 function more_args(){
   for($i = 0; $i <func_num_args(); $i++){          //使用for循环
     echo "第".$i."个参数：".func_get_arg($i)."<br>";    //分别输出传入函数的每个参数
   }
 }
 more_args(1, 2, 3);       //调用函数并输入多个参数
?>

The output result is as follows:

The 0th parameter: 1

The first parameter: 2

The second parameter: 3

The above two examples are implemented With the same function, you can get any number of parameter lists in the function and use them in the function.

It can be seen from the above example that the variable number of parameters of the PHP function has the following forms:

func_num_args Returns the total number of parameters

func_get_arg Return an item in the parameter list

func_get_args Return an array containing the function parameter list

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