23. Metacharacters - Quantifiers: Intervals

• Finally, the last of the quantifiers is the interval, or range.
• Intervals are constructed using a:

    {min, max}
          

  structure, where min is the minimum number of times the qualified character can match, and max is the maximum. If that character is found a number of times anywhere in that interval, then the match will succeed.
• This gives us a way of making our search for phone numbers much more precise than before. Remember that we were using:

    [0-9]*[ -]*[0-9]*
          

• Now we can modify this to be:

    [0-9]{4}[ -]*[0-9]{4}
          

• Notice that the interval can also be used like an "exact number of times" requirement - in this case, we want to match any digit, then another digit, etc. 4 times, then zero or more spaces or dashes, and then a digit, another digit, etc, again, 4 times. This is much more like what we are looking for!