␡
- 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
This chapter is from the book
2.21 Embedding Expressions Within Strings
The #{} notation makes this easy. We need not worry about converting, appending, and concatenating; we can interpolate a variable value or other expression at any point in a string:
puts "#{temp_f} Fahrenheit is #{temp_c} Celsius"
puts "The discriminant has the value #{b*b - 4*a*c}."
puts "#{word} is #{word.reverse} spelled backward."
Bear in mind that full statements can also be used inside the braces. The last evaluated expression will be the one returned.
str = "The answer is #{ def factorial(n)
n==0 ? 1 : n*factorial(n-1)
end
answer = factorial(3) * 7}, of course."
# The answer is 42, of course.
There are some shortcuts for global, class, and instance variables, in which case the braces can be dispensed with:
print "$gvar = #$gvar and ivar = #@ivar."
Note that this technique is not applicable for single-quoted strings (because their contents are not expanded), but it does work for double-quoted here-documents and regular expressions.