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This article mainly introduces how to receive the parameters of the Perl function, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let Xiaobian take you to understand.

Parameter receiving method of Perl function

Pick Perl again

Original: http://www.linuxsir.org/bbs/showthread.php?t=78216

Perl function and scope

Syntax:

SubsubroutineName

{

The my (@ argsTosubroutine) = @ _; # argument is passed to the Perl function in this way

& doStuff;# executor

Return (@ returnValue); #

}

The special variable @ _ is the parameter stack, which is local data for the called subroutine. Put the parameters into @ _ each time the subroutine is called. @ _ works much like the stacks in c and C++. Because the parameter stack is an array, there is no limit to the number of arguments passed to the Perl function. And every parameter is a scalar. When a subroutine is called, the length of the parameter stack is irrelevant. No matter what parameter is passed to the reader's subroutine, Perl will be responsible for generating @ _, and the subPerl function will decide whether to accept the parameter or not.

◆ operation parameter stack:

In Perl, the subscript of any array starts at 0.)

@ _, like other types of arrays, can be accessed through subscripts.

You can also use the shift and popPerl functions to access @ _. Shift and pop actually mean that shift (@ _) pop (@ _) is two Perl functions that operate on the parameter stack. Indicates whether the parameter stack is manipulated from the top or bottom of the stack. Each time they are called, they take * parameters (shift) or do the latter parameter (pop). Then shorten @ _ as you continue execution by storing the parameter in the variable on the left.

Local @ _ stack. This feature allows the Perl function to be called within a Perl function without having to worry about the impact of the Perl function at this level on the lower-level Perl function. This flexibility allows Perl to use recursive programs

The return value stack is the way Perl returns the value to the caller of the subroutine. @ values=subroutine ($arguments). Like the parameter stack, the return value stack is also an array.

There are two main ways for the child Perl function to return the value to the main Perl function:

◆ uses a special Perl function to return

◆ uses the default method (that is, look at an expression of the subroutine).

1.Return keyword

The Return keyword allows you to immediately break the sub-Perl function and return the value inside the parameter stack to the calling Perl function.

2. Return by default

If there is no return statement in the Perl function, the * sentence of the subroutine actually returns the value stack

3.Wantarray

The Perl function is the Perl function in Perl that can make the sub-Perl function perform dual responsibilities. Wantarray can determine whether a Perl function is used in an array or scalar environment.

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