How to check whether a string contains a substring in Ruby

Question

I have a string variable with content:

varMessage =   
            \"hi/thsid/sdfhsjdf/dfjsd/sdjfsdn\\n\"


            \"/my/name/is/balaji.so\\n\"
                 


        

Answer 1

You can use the String Element Reference method which is []

Inside the [] can either be a literal substring, an index, or a regex:

> s='abcdefg'
=> "abcdefg"
> s['a']
=> "a"
> s['z']
=> nil

Since nil is functionally the same as false and any substring returned from [] is true you can use the logic as if you use the method .include?:

0> if s[sub_s]
1>    puts "\"#{s}\" has \"#{sub_s}\""
1> else 
1*    puts "\"#{s}\" does not have \"#{sub_s}\""
1> end
"abcdefg" has "abc"

0> if s[sub_s]
1>    puts "\"#{s}\" has \"#{sub_s}\""
1> else 
1*    puts "\"#{s}\" does not have \"#{sub_s}\""
1> end
"abcdefg" does not have "xyz" 

Just make sure you don't confuse an index with a sub string:

> '123456790'[8]    # integer is eighth element, or '0'
=> "0"              # would test as 'true' in Ruby
> '123456790'['8']  
=> nil              # correct

You can also use a regex:

> s[/A/i]
=> "a"
> s[/A/]
=> nil