5 common mistakes in Perl

I am using perl+mdbm+sPRead to make things recently.

php has been used for a long time. I have used python and ruby. I have never touched the classic scripting language perl. Now I am reading the textbook like a primary school student.

I found that perl is indeed much more difficult. Nothing else makes me make mistakes so often.

1. The first common mistake is: outputting content to a file. The standard syntax is:

print STDERR "this is an apple.";

I usually write it as

print STDERR, "this is an apple.";

Always add an extra comma. To be honest, I rarely make mistakes repeatedly, but I just can't remember this one.

2. The second common mistake is: often missing the arrow referenced by Hash.

should be written as

print $hash->{$key};

I often write as

print $hash{$key};

3. The third common mistake is: String comparison:

After using PHP for a long time, I always use two equal signs to compare strings. This is wrong. The correct way to write it is

if($var eq "hello") {
                                                                                                                                             }

This will lead to logical errors that are difficult to detect.见4. The fourth common error:

IF statement without parentheses (all pHP is bad)

The correct way is:

IF ($ var) {

Print "yes";

}

I often write

if($var)

print "yes";

5. There is another mistake, which is not brought from php, and most people probably won't make it: missing a semicolon.

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