Representation
'string literal in single quote' |
"escaped string \t \n" |
%q[a string] |
single quoted string |
%Q[escaped \t] |
double quoted string |
<<EOF {{multiline string}} EOF |
double quoted string |
<<'EOF' {{multiline string}} EOF |
single quoted string |
<<-EOF {{multiline string}} EOF |
preserve line indentation |
<<EOF.#{method} {{multiline string}} EOF |
method is defined as a String instance method |
<<eof str1 #{eof2} str2 eof |
here doc can be nested |
Iterate Line, Byte, Char
each_char |
{|char| puts char} |
each_line |
{|line| puts line} |
each_byte |
{|byte| puts byte} |
each_line.with_index |
{|line, index| puts line, index} |
s.scan(/./) {|char| puts char} |
. matches a char |
Specialized string comparison
alias old_compare <=> |
* use the old_compare in the new <=> method |
redefine == method |
Redefine <=> method under String class |
Tokenize
s1 = “It was a dark”; s1.split |
# ["It", "was", "dark"] |
s2.split(“, “) |
use a string |
s3.split(/ and /) |
use regex |
s = “alpha,beta,gamma,,” |
s.split(“,”,4) |
#["alpha", "beta", "gamma", ","] - rest of the string |
s.split(“,”,-1) |
["alpha", "beta", "gamma", "", ""] - empty matches |
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Scan a string
s ="a,a,a"; s.scan("a") |
=> ["a", "a", "a"] |
s.scan(/\w+/) |
regex or string |
str.scan(/\w+/) {|x| puts x } |
each scan result is passed to the block |
StringScanner |
require 'strscan' |
ss = StringScanner.new(str) |
str = “Watch how I soar!” |
ss.bol? |
beginning of line |
ss.eos? |
end of string |
ss.pos, ss.pos= |
query or set current position |
ss.match, ss.matched?, ss.matched |
check if a match exists at pos |
ss.pre_match, ss.post_match |
check a pre or post match - only if matched? |
ss.rest, ss.rest? |
get the rest of the string |
ss.reset, ss.terminate |
move to beginning or end |
ss.scan, ss.unscan |
scan and unscan |
ss.exist? |
check if a substring exits in the rest |
StringScanner acts like a file pointer - it forwards the pointer when there is a match, thus allowing for multiple scan capabilities on the same string.
* ususally methods ending with ? returns boolean
Sub strings
s[7,4] |
start index, length |
s[-3,3] |
index from end (end is -1), length |
s[8..13] |
index range |
s[/foo/]; s["foo"] |
regex or string |
s[4] |
single index |
s[8..13]= |
All above sub string look ups can also be used for assignment |
Substitute / replace a string
s.sub(pattern, replacement) |
pattern - regex or string |
s.sub(pattern) {block} |
each match of the pattern is passed to the block |
special symbols \1, \2 can be used in replacement string; gsub is a method which replaces all matches while sub does it only for first match
sub!, gsub! - inplace replacements
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Search a string
s.index(string|regex) => int |
s.rindex(string|regex) => int |
s.include?(string|regex) =>bool |
s.scan(str|reg) => array |
ASCII and Char conversion
"A".ord => 65 |
65.chr => "A" |
233.chr('UTF-8') => "é" |
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