How to turn on Perl warnings? Why is that important?

Q

✍: Guest

A

Perl is very forgiving of strange and sometimes wrong code, which can mean hours spent searching for bugs and weird results. Turning on warnings helps uncover common mistakes and strange places and save a lot of debugging time in the long run. There are various ways of turning on Perl warnings:

For Perl one-liner, use -w option on the command line.
On Unix or Windows, use the -w option in the shebang line (The first # line in the script). Note: Windows Perl interpreter may not require it.
For other systems, choose compiler warnings, or check compiler documentation.

2013-08-27, 2340👍, 0💬

How do I do fill_in_the_blank for each file in a directory?
How do I do fill_in_the_blank for each file in a directory? Here's code that just prints a listing of every file in the current directory: #!/usr/bin/perl -w opendir(DIR, "."); @files = readdir(DIR); closedir(DIR); foreach $file (@files) { print "$file\n"; } 2013-08-23, 2955👍, 0💬

What happens when you return a reference to a private variable?
What happens when you return a reference to a private variable? Perl keeps track of your variables, whether dynamic or otherwise, and doesn't free things before you're done using them. 2013-08-27, 2409👍, 0💬

What is Perl one-liner?
What is Perl one-liner? There are two ways a Perl script can be run: --from a command line, called one-liner, that means you type and execute immediately on the command line. You'll need the -e option to start like "C:\ %gt perl -e "print "Hello";". One-liner doesn't mean one Perl statement. One-lin... 2013-08-26, 2409👍, 0💬

How to turn on Perl warnings? Why is that important?
How to turn on Perl warnings? Why is that important? Perl is very forgiving of strange and sometimes wrong code, which can mean hours spent searching for bugs and weird results. Turning on warnings helps uncover common mistakes and strange places and save a lot of debugging time in the long run. The... 2013-08-27, 2341👍, 0💬

I want users send data by formmail but when they send nothing or call it from web site they will see error ....
I want users send data by formmail but when they send nothing or call it from web site they will see error. codes in PHP like this: if (isset($HTTP_POST_VARS)){ .......... } else{ echo ("error lalalalal") } How it will look in perl? In php it will be like if (isset($HTTP_POST_VARS)){ .... } In perl,... 2013-08-30, 2324👍, 0💬

Assuming both a local($var) and a my($var) exist, what's the difference between ${var} and ${"var"}?
Assuming both a local($var) and a my($var) exist, what's the difference between ${var} and ${"var"}? ${var} is the lexical variable $var, and ${"var"} is the dynamic variable $var. Note that because the second is a symbol table lookup, it is disallowed under `use strict "refs"'. The words global, lo... 2013-08-26, 2310👍, 0💬

What is the output of the following Perl program?
What is the output of the following Perl program? 1 $p1 = "prog1.java"; 2 $p1 =~ s/(.*)\.java/$1.cpp/; 3 print "$p1\n"; prog1.cpp 2013-08-30, 2233👍, 0💬

What are scalar data and scalar variables?
What are scalar data and scalar variables? Perl has a flexible concept of data types. Scalar means a single thing, like a number or string. So the Java concept of int, float, double and string equals to Perl's scalar in concept and the numbers and strings are exchangeable. Scalar variable is a Perl ... 2013-08-28, 2222👍, 0💬

Assuming $_ contains HTML, which of the following substitutions will remove all tags in it?
Assuming $_ contains HTML, which of the following substitutions will remove all tags in it? 1.s/<.*>//g; 2.s/<.*?>//gs; 3.s/<\/?[A-Z]\w*(?:\s+[ A-Z]\w*(?:\s*=\s*(?:(["']).*?\ 1|[\w-.]+))?)*\s*>//gsi x;You can't do that. If it weren't for HTML comments, imprope... 2013-08-29, 2174👍, 0💬

All rights in the contents of this web site are reserved by the individual author. fyicenter.com does not guarantee the truthfulness, accuracy, or reliability of any contents.