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→Freezing a Ruby String
myString << "hello"
TypeError: can't modify frozen string
</pre>
== Accessing String Elements ==
Fragments of a Ruby string can be accessed using the [] method of the ''String class''. One use for this method is to find if a particular sequence of characters exists in a string. If a match is found the sequence is returned, otherwise ''nil'' is returned:
<pre>
myString = "Welcome to Ruby!"
myString["Ruby"]
=> "Ruby"
myString["Perl"]
=> nil
</pre>
Pass an integer through to the [] method and the ASCII code of the character at that location in the string (starting at zero) will be returned. This can be converted back to a character using the ''chr'' method:
<pre>
myString[3].chr
=> "c"
</pre>
You can also pass through a start position and a number of characters to extract a subsection of a string:
<pre>
myString[11, 4]
=> "Ruby"
</pre>
You can also use a Range to specify a group of characters between start and end points:
<pre>
myString[0..6]
=> "Welcome"
</pre>
The location of a matching substring can be obtained using the ''index'' method:
<pre>
myString.index("Ruby")
=> 11
</pre>
