Check whether a string contains a substring

Question

How can I check whether a given string contains a certain substring  using Perl   More specifically  I want to see whether s1 domain com is present in the given string variable

User · Answer

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

User · Answer

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

User · Answer

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

[string] Check whether a string contains a substring

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