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This article focuses on "what are the special skills of Perl language programming", friends who are interested may wish to have a look. The method introduced in this paper is simple, fast and practical. Next, let the editor take you to learn "what are the special skills of Perl language programming?"

Implemented in Perl, you can write:

While ($line=) {

Print$line

}

The program is very concise at first, but what does each statement mean? Simply put, it is a dedicated file handle, which in this case belongs to the standard input cache (called STDIN), usually connected to the keyboard. Every time we assign a value to the variable $line, we take out the first line in the STDIN cache and put it in $line. When the last line of the cache is reached, the (EOF) file end identifier whose while statement determines that the condition is false is fetched. The rest of the program is simple and can be explained this way. Now that we have put the input into the $line variable, we can print it to the screen using the print function. Or, more accurately, print to the standard input cache that is usually connected to the monitor. Both the standard input and output caches can be redirected, for example, to a file that holds the program results, and if you are working with text, you can usually consider this to be equivalent to the keyboard and monitor.

You might think this program is already the shortest, but by using perl's special variables, it can be even shorter.

What are the special skills of Perl language programming

Default data variable: $_

Perl has many special variables that are automatically assigned while the program is running and can be used to access some information about the program itself, such as the program name or process ID number, command line arguments, or the result of the last expression. The most frequently used and perhaps the most useful of these variables is the default variable $_. If you are not specified in the program, the default variable is used as an unassigned function variable to hold the operation results of some perl structures and functions. This may sound confusing before you are familiar with perl, but it is really powerful. We can use the variable $_ to cancel the $line variable in the program:

While () {

Print$_

}

This program is equivalent to the previous one, even though we used only one file handle in the test conditional while statement. The program stores the input to the default variable, so we can access the input information with the variable $_ when we want to output. But we can also make the program shorter, remember I said, $_ is a default variable for an undefined implementation of a function, so printing is one of its functions, so we can now write the program like this:

While () {

Print

}

At this point, I believe you have a deeper understanding of "what are the special skills of Perl programming"? you might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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