- 2.1 Representing Ordinary Strings
- 2.2 Representing Strings with Alternate Notations
- 2.3 Using Here-Documents
- 2.4 Finding the Length of a String
- 2.5 Processing a Line at a Time
- 2.6 Processing a Byte at a Time
- 2.7 Performing Specialized String Comparisons
- 2.8 Tokenizing a String
- 2.9 Formatting a String
- 2.10 Using Strings As IO Objects
- 2.11 Controlling Uppercase and Lowercase
- 2.12 Accessing and Assigning Substrings
- 2.13 Substituting in Strings
- 2.14 Searching a String
- 2.15 Converting Between Characters and ASCII Codes
- 2.16 Implicit and Explicit Conversion
- 2.17 Appending an Item Onto a String
- 2.18 Removing Trailing Newlines and Other Characters
- 2.19 Trimming Whitespace from a String
- 2.20 Repeating Strings
- 2.21 Embedding Expressions Within Strings
- 2.22 Delayed Interpolation of Strings
- 2.23 Parsing Comma-Separated Data
- 2.24 Converting Strings to Numbers (Decimal and Otherwise)
- 2.25 Encoding and Decoding rot13 Text
- 2.26 Encrypting Strings
- 2.27 Compressing Strings
- 2.28 Counting Characters in Strings
- 2.29 Reversing a String
- 2.30 Removing Duplicate Characters
- 2.31 Removing Specific Characters
- 2.32 Printing Special Characters
- 2.33 Generating Successive Strings
- 2.34 Calculating a 32-Bit CRC
- 2.35 Calculating the MD5 Hash of a String
- 2.36 Calculating the Levenshtein Distance Between Two Strings
- 2.37 Encoding and Decoding base64 Strings
- 2.38 Encoding and Decoding Strings (uuencode/uudecode)
- 2.39 Expanding and Compressing Tab Characters
- 2.40 Wrapping Lines of Text
- 2.41 Conclusion
This chapter is from the book
This chapter is from the book
This chapter is from the book
2.23 Parsing Comma-Separated Data
Comma-delimited data are common in computing. It is a kind of "lowest common denominator" of data interchange used (for example) to transfer information between incompatible databases or applications that know no other common format.
We assume here that we have a mixture of strings and numbers and that all strings are enclosed in quotes. We further assume that all characters are escaped as necessary (commas and quotes inside strings, for example).
The problem becomes simple because this data format looks suspiciously like a Ruby array of mixed types. In fact, we can simply add brackets to enclose the whole expression, and we have an array of items.
string = gets.chop!
# Suppose we read in a string like this one:
# "Doe, John", 35, 225, "5'10\"", "555-0123"
data = eval("[" + string + "]") # Convert to array
data.each {|x| puts "Value = #{x}"}
This fragment produces the following output:
Value = Doe, John Value = 35 Value = 225 Value = 5' 10" Value = 555-0123
For a more heavy-duty solution, refer to the CSV library (which is a standard library). There is also a somewhat improved tool called FasterCSV. Search for it online; it is not part of the standard Ruby distribution.