001-6. Regular expression
@ # Regular expression does only 2 task(finding and replacing) @ # "." means one character # If I want to find 3 characters, I use "..." @ # [] means finding "one character" inside of target source text # With [abc]d, regular expression finds "ad", "bd", "cd" # It's bothering to manually write each character # for continuous numbers or continuous alphabets, # we can use range syntax by using "-" # For example, [a-z] finds one character from a to z in text # and [1-9] finds one character from 1 to 9 in text @ # [^] finds one character # (which is not included by character which is included inside of[]) in text # For example, [^abc]d doesn't find ad, bd, cd, # and if ed, fd in text, [^abc]d chooses ed, fe # [^a-z] finds all characters (which are not lowercase alphabet) in text @ # ^ symbol (outside of []) finds the first of character or line of sentence # This is rarely used @ # $ symbol finds the last of character or line of sentence # This is rarely used @ # Designating quantity by regular expression @ # "?" affects one character which is located in front of "?" # Later, we will use [] in front of "?" to desinate range in front of "?" # "?" means occurring of 0 time or 1 time # For example, colou?r finds color and colour @ # "*" affects one character which is located in front of "*" # Later, we will use [] in front of "*" to desinate range in front of "*" # "*" means occurring of all times over 0 time # For example, ab*c finds ac, abc, abbc, abbbc @ # "+" affects one character which is located in front of "+" # Later, we will use [] in front of "+" to desinate range in front of "+" # "+" means occurring of all times over 1 time # For example, ab+c finds abc, abbc, abbbc @ # We can grab stock market site # by using above regular expression symbol finding patterns in text # So, we can predict future change of stock by using past data with regular expression