5 Common bugs in Perl-Application Tips

I'm doing something with Perl+mdbm+spread recently.

PHP has been used for a long time, Python and Ruby have been used, the classic scripting language has not been touched by Perl, now in the same way as a pupil holding a textbook gnawing.

It's a lot harder to find Perl. Something else didn't make me make a mistake so often.

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

Print STDERR "This is an apple."

I usually write

Print STDERR, "This is a apple.";

Always play a comma more. Frankly speaking, I rarely make mistakes repeatedly, but I just can't remember this place.

2. The second common error is: Often omitting the arrows that hash references.

Should have been written

Print $hash->{$key};

I often write

Print $hash {$key};

3. A third common error is: string comparisons:

Use PHP for a long time, always using two equals sign to compare strings. This is wrong. The correct wording is

if ($var eq "Hello") {
print "World";
}

I often write:

if ($var = = "Hello") {
print "World";
}

This can lead to logic errors that are difficult to find.

4. A fourth common error:

If statement with no parentheses (all PHP bad)

The correct wording is:

if ($var)
{
print "yes";
}

I often write

if ($var)
print "yes";

5. There is also a mistake, not from PHP brought over, the average person will not commit: the omission of a semicolon.