Check whether a string contains a substring
To find out if a string contains substring you can use the index
function:
if (index($str, $substr) != -1) {
print "$str contains $substr\n";
}
It will return the position of the first occurrence of $substr
in $str
, or -1 if the substring is not found.
Another possibility is to use regular expressions which is what Perl is famous for:
if ($mystring =~ /s1\.domain\.com/) {
print qq("$mystring" contains "s1.domain.com"\n);
}
The backslashes are needed because a .
can match any character. You can get around this by using the \Q
and \E
operators.
my $substring = "s1.domain.com";
if ($mystring =~ /\Q$substring\E/) {
print qq("$mystring" contains "$substring"\n);
}
Or, you can do as eugene y stated and use the index function.
Just a word of warning: Index returns a -1
when it can't find a match instead of an undef
or 0
.
Thus, this is an error:
my $substring = "s1.domain.com";
if (not index($mystring, $substr)) {
print qq("$mystring" doesn't contains "$substring"\n";
}
This will be wrong if s1.domain.com
is at the beginning of your string. I've personally been burned on this more than once.
Case Insensitive Substring Example
This is an extension of Eugene's answer, which converts the strings to lower case before checking for the substring:
if (index(lc($str), lc($substr)) != -1) {
print "$str contains $substr\n";
}