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Ruby Symbols and Strings

·456 words·3 mins·
Programming Ruby Symbols Strings Programming
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Ruby Symbols and Strings
#

Symbols and strings are both used to represent text in Ruby, but they have different characteristics and use cases.

Strings
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Strings are mutable sequences of characters:

# String creation
str1 = "Hello"
str2 = 'World'
str3 = %q(Another way)
str4 = %Q(With interpolation: #{str1})

# String interpolation (only works with double quotes)
name = "Alice"
puts "Hello, #{name}!"

# Multi-line strings
multiline = <<-TEXT
  This is a
  multi-line
  string
TEXT

# String concatenation
full_name = "John" + " " + "Doe"
full_name << " Jr."  # Append in place

Common String Methods
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Ruby provides many useful string manipulation methods:

str = "hello world"

# Case manipulation
str.upcase        # "HELLO WORLD"
str.downcase      # "hello world"
str.capitalize    # "Hello world"
str.swapcase      # "HELLO WORLD"

# Checking content
str.include?("world")   # true
str.start_with?("hello") # true
str.end_with?("world")   # true
str.empty?               # false

# Transformations
str.reverse       # "dlrow olleh"
str.split         # ["hello", "world"]
str.gsub("world", "ruby")  # "hello ruby"

# Length and indexing
str.length        # 11
str[0]            # "h"
str[0..4]         # "hello"
str[-1]           # "d"

Symbols
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Symbols are immutable, interned strings that start with a colon:

# Symbol creation
symbol1 = :name
symbol2 = :email
symbol3 = :"with spaces"

# Symbols are unique - same symbol always has same object_id
:name.object_id == :name.object_id  # true

# Strings are not unique
"name".object_id == "name".object_id  # false

When to Use Symbols vs Strings
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Guidelines for choosing between symbols and strings:

# Use symbols for:
# - Hash keys
person = { name: "Alice", age: 30, city: "NYC" }

# - Method names and identifiers
obj.send(:method_name)

# - Constants that won't change
STATUS_ACTIVE = :active
STATUS_INACTIVE = :inactive

# Use strings for:
# - User input and output
user_input = gets.chomp
puts "Welcome, #{user_input}"

# - Text that will be manipulated
message = "Hello"
message << ", World!"

# - Data from external sources
data = File.read("file.txt")

Converting Between Symbols and Strings
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Easy conversion between the two types:

# String to symbol
"hello".to_sym    # :hello
"hello".intern    # :hello

# Symbol to string
:hello.to_s       # "hello"
:hello.id2name    # "hello"

# Hash keys conversion
hash = { "name" => "Alice", "age" => 30 }
hash.transform_keys(&:to_sym)  # { name: "Alice", age: 30 }

String Formatting
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Different ways to format strings in Ruby:

# sprintf/format
sprintf("Hello, %s", "World")
"Hello, %s" % "World"

# Multiple values
"Name: %s, Age: %d" % ["Alice", 30]

# Padding and alignment
"%10s" % "hi"     # "        hi"
"%-10s" % "hi"    # "hi        "
"%05d" % 42       # "00042"

# Floating point
"%.2f" % 3.14159  # "3.14"

String Encoding
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Ruby supports multiple character encodings:

# Check encoding
"hello".encoding  # #<Encoding:UTF-8>

# Force encoding
str = "café"
str.encoding                     # UTF-8
str.force_encoding("ASCII-8BIT")

# Convert encoding
str.encode("ISO-8859-1")

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