Ruby Lesson 1 Section 2 of 4: String Methods

Section Topics:

• .length 
• .reverse
• .upcase and .downcase 

So methods are like commands except for the following (that I know of): 

1. A period is used before a method 
2. You can have more than one method on a line and Ruby will follow the sequence from left to right

Remember in Ruby everything is case sensitive and just like with commands capitilizing any letter in a method will cause an error. 

So to explain what the 4 methods in this section does. 

.length returns the number of characters in string including numbers, letters, spaces, and symbols. 

Example: 

1. Input: "David" .length
   
   Ouput: 5
2. Input: "David ".length
   
   Ouput: 6

Note: Like setting variables the spaces between the method and string from the period does not affect the output. For instance ( "David"  .  length ) OR ("David".    length) will both give us an output of 5. 

.reverse returns the string backwards. 

Example:

1. Input: "David" .reverse
   
   Ouput: "divaD"

. upcase capitalizes every letter in the string and .downcase lowercases every letter in the string. 

Examples:

1. Input: "David" .upcase
   
   Ouput: DAVID
2. Input: "David" .downcase
   
   Ouput: david

Extras 

Remember when I said methods can be on the same line as a command? And that Ruby will do them in order of left to right? Well I did some testing on matter.

Tests: 

1. Input: print "david" .upcase
   
   Ouput: DAVID
   
   Lesson: Command and methods can exist on the same line.
2. Input: print "david" .upcase.downcase
   
   Ouput: david
   
   Lesson: Ruby follows commands/methods from left to right
3. Input: print "david" .upcase.downcase.length
   
   Ouput: 5
   
   Lesson: Same as test 2
4. Input: print "david" .length.upcase.downcase
   
   Ouput: error: undefined method 'upcase' for 5
   
   Lesson: Same as test 2 and that the .upcase and .downcase methods will cause error for numbers
5. Input: "david5" .upcase
   
   Ouput: DAVID5
   
   Lesson: Tested for .downcase and with symbols. .downcase and .upcase will work as long as there is a letter in the string.
6. Input: "david".upcase print "hi"
   
   Ouput: error
   
   Lesson: Commands cannot be after methods
7. Input: print "david".upcase
             print "david".upcase
   
   Ouput: DAVIDDAVID
   
   Input: puts "david".upcase
             puts "david".upcase
   
   Ouput: DAVID
               DAVID
   
   Lesson: Commands do not get overwritten by methods following it. This is an important one since all the other tests could have been concluded that the command was overwritten.