a = "42" # => '42'
a.to_i # => 42
# But if you might not have a number in your String, you should rather
# use this instead, as to_i doesn't throw an Error:
"42test123".to_i # => 42
Integer("42test123") # => ArgumentError
Integer("42") # => 42
Integer('5abc') #=> ArgumentError: invalid value for Integer(): "5abc"
Integer('5') #=> 5a = "42" # => '42'
a.to_i # => 42
# But if you might not have a number in your String, you should rather
# use this instead, as to_i doesn't throw an Error:
"42test123".to_i # => 42
Integer("42test123") # => ArgumentError
Integer("42") # => 42
Integer('5abc') #=> ArgumentError: invalid value for Integer(): "5abc"
Integer('5') #=> 5