[Ruby] string processing

1. Return the length of the string
Str. Length => integer

2. Determine whether the string contains another string
Str. Include? Other_str => true or false

"Hello". Include? "Lo" # => true
"Hello". Include? "Ol" # => false
"Hello". Include? ? H #=> true

3. String insertion:
Str. insert (index, other_str) => Str

"ABCD". insert (0, 'x') # => "xabcd"
"ABCD". insert (3, 'x') # => "abcxd"
"ABCD". insert (4, 'x') # => "abcdx"
"ABCD". insert (-3, 'x') # => "abxcd"
"ABCD". insert (-1, 'x') # => "abcdx"

4. String separation. The default Delimiter is space.
Str. Split (pattern =$;, [limit]) => anarray

"Now's the time". Split # => ["Now's", "the", "Time"]
& Quot; 1, 2.34, 56, 7 & quot ". split (% R {,/S *}) # => ["1", "2.34", "56", "7"]
"Hello". Split (//) # => ["H", "E", "L", "L", "O"]
"Hello". Split (//, 3) # => ["H", "E", "llo"]
"Hi mom". Split (% R {/S *}) # => ["H", "I", "M", "O", "M"]

"Mellow yellow". Split ("ello") # => ["M", "w y", "W"]
"1, 2, 3, 4,". Split (',') # => ["1", "2", "", "3", "4"]
"1, 2, 3, 4,". Split (',', 4) # => ["1", "2", "", "3, 4,"]

5. String replacement
Str. gsub (pattern, replacement) => new_str
Str. gsub (pattern) {| match | block} => new_str

"Hello". gsub (/[aeiou]/, '*') # => "H * ll *" # Replace the vowel with the * sign
"Hello ". gsub (/([aeiou])/, '</1>') # => "H <E> ll <o>" # enclose the vowel with Angle brackets, /1 indicates that the original characters are retained ???
"Hello". gsub (/./) {| S | s [0]. to_s + ''}#=>" 104 101 108 108"

String replacement 2:
Str. Replace (other_str) => Str
S = "hello" # => "hello"
S. Replace "world" # => "world"

6. String deletion:

Str. Delete ([other_str] +) => new_str
"Hello". Delete "L", "Lo" # => "Heo"
"Hello". Delete "Lo" # => "he"
"Hello". Delete "aeiou", "^ e" # => "hell"
"Hello". Delete "ej-M" # => "ho"

7. Remove leading and trailing Spaces
Str. lstrip => new_str

"Hello". lstrip # => "hello"
"Hello". lstrip # => "hello"

8. String Matching
Str. Match (pattern) => matchdata or nil

9. String Inversion
Str. Reverse => new_str

"Stressed". Reverse # => "desserts"

10. Remove duplicate characters
Str. Squeeze ([other_str] *) => new_str
"Yellow Moon". Squeeze # => "yelow mon" # All repeated characters in the string are removed by default.
"Now is the". Squeeze ("") # => "now is the" # Remove repeated spaces in the string
"Putters shoot bils". Squeeze ("M-z") # => "puters shot bils" # Remove repeated characters in the specified range

11. Convert to numbers
Str. to_ I => Str
"12345". to_ I # => 12345

Differences between Chomp and chop:
Chomp: Remove/N or/R at the end of the string.
Chop: removes the last character at the end of the string, whether it is/n/R or a common character.

"Hello". Chomp # => "hello"
"Hello/N". Chomp # => "hello"
"Hello/R/N". Chomp # => "hello"
"Hello/n/R". Chomp # => "Hello/N"
"Hello/R". Chomp # => "hello"
"Hello". Chomp ("llo") # => "he"

"String/R/N". Chop # => "string"
"String/n/R". Chop # => "String/N"
"String/N". Chop # => "string"
"String". Chop # => "strin"
"X". Chop. Chop # => ""