Tokenize a string
You are encouraged to solve this task according to the task description, using any language you may know.
Separate the string "Hello,How,Are,You,Today" by commas into an array so that each index of the array stores a different word. Display the words to the 'user', in the simplest manner possible, separated by a period. To simplify, you may display a trailing period.
Ada
with Ada.Strings.Fixed; use Ada.Strings.Fixed; with Ada.Text_Io; use Ada.Text_Io; procedure Parse_Commas is Source_String : String := "Hello,How,Are,You,Today"; Index_List : array(1..256) of Natural; Next_Index : Natural := 1; begin Index_List(Next_Index) := 1; while Index_List(Next_Index) < Source_String'Last loop Next_Index := Next_Index + 1; Index_List(Next_Index) := 1 + Index(Source_String(Index_List(Next_Index - 1)..Source_String'Last), ","); if Index_List(Next_Index) = 1 then Index_List(Next_Index) := Source_String'Last + 2; end if; Put(Source_String(Index_List(Next_Index - 1)..Index_List(Next_Index)-2) & "."); end loop; end Parse_Commas;
C++
Standard: ANSI C++
Compiler: GCC g++ (GCC) 3.4.4 (cygming special)
Library: STL
This is not the most efficient method as it involves redundant copies in the background, but it is very easy to use. In most cases it will be a good choice as long as it is not used as an inner loop in a performance critical system.
Note doxygen tags in comments before function, describing details of interface.
#include <string> #include <vector> /// \brief convert input string into vector of string tokens /// /// \note consecutive delimiters will be treated as single delimiter /// \note delimiters are _not_ included in return data /// /// \param input string to be parsed /// \param delims list of delimiters. std::vector<std::string> tokenize_str(const std::string & str, const std::string & delims=", \t") { using namespace std; // Skip delims at beginning, find start of first token string::size_type lastPos = str.find_first_not_of(delims, 0); // Find next delimiter @ end of token string::size_type pos = str.find_first_of(delims, lastPos); // output vector vector<string> tokens; while (string::npos != pos || string::npos != lastPos) { // Found a token, add it to the vector. tokens.push_back(str.substr(lastPos, pos - lastPos)); // Skip delims. Note the "not_of". this is beginning of token lastPos = str.find_first_not_of(delims, pos); // Find next delimiter at end of token. pos = str.find_first_of(delims, lastPos); } return tokens; }
here is sample usage code:
#include <iostream> int main() { using namespace std; string s("Hello,How,Are,You,Today"); vector<string> v(tokenize_str(s)); for (unsigned i = 0; i < v.size(); i++) cout << v[i] << "."; cout << endl; return 0; }
E
".".rjoin("Hello,How,Are,You,Today".split(","))
Forth
There is no standard string split routine, but it is easily written. The results are saved temporarily to the dictionary.
: split ( str len separator len -- tokens count ) here >r 2swap begin 2dup 2, \ save this token ( addr len ) 2over search \ find next separator while dup negate here 2 cells - +! \ adjust last token length 2over nip /string \ start next search past separator repeat 2drop 2drop r> here over - ( tokens length ) dup negate allot \ reclaim dictionary 2 cells / ; \ turn byte length into token count : .tokens ( tokens count -- ) 0 ?do dup 2@ type ." ." cell+ cell+ loop drop ; s" Hello,How,Are,You,Today" s" ," split .tokens \ Hello.How.Are.You.Today.
Java
Compiler: JDK 1.0 and up
There is multiple way to tokenized a string in Java. The first with a split the String into an array of String, and the other way to give a Enumerator. The second way given here will skip any empty token. So if two commas are given in line, there will be an empty string in the array given by the split function but no empty string with the StringTokenizer object.
String toTokenize = "Hello,How,Are,You,Today"; //First way String word[] = toTokenize.split(","); for(int i=0; i<word.length; i++) { System.out.print(word[i] + "."); } //Second way StringTokenizer tokenizer = new StringTokenizer(toTokenize, ","); while(tokenizer.hasMoreTokens()) { System.out.print(tokenizer.nextToken() + "."); }
JavaScript
Interpreter: Firefox 2.0
var str = "Hello,How,Are,You,Today"; var tokens = str.split(","); alert( tokens.join(".") );
Perl
Interpreter: Perl any 5.X
As a one liner without a trailing period, and most efficient way of doing it as you don't have to define an array.
print join('.', split(/,/, "Hello,How,Are,You,Today"));
If you needed to keep an array for later use, again no trailing period
my @words = split(/,/, "Hello,How,Are,You,Today"); print join('.', @words);
If you really want a trailing period, here is an example
my @words = split(/,/, "Hello,How,Are,You,Today"); print $_.'.' for (@words);
PHP
Interpreter: PHP any 5.x
<?php $str = 'Hello,How,Are,You,Today'; $arr = array_fill_keys(explode(',', $str), 0); echo implode('.', array_keys($arr)); ?>
Pop11
Natural solution in Pop11 uses lists:
;;; Declare and initialize variables lvars str='Hello,How,Are,You,Today'; lvars ls = [], i, j = 1; ;;; Iterate over string for i from 1 to length(str) do ;;; If comma if str(i) = `,` then ;;; Preped word (substring) to list cons(substring(j, i - j, str), ls) -> ls; i + 1 -> j; endif; endfor; ;;; Preped final word (if needed) if j <= length(str) then cons(substring(j, length(str) - j + 1, str), ls) -> ls; endif; ;;; Reverse the list rev(ls) -> ls;
Since the task requires to use array we convert list to array
;;; Put list elements and lenght on the stack destlist(ls); ;;; Build a vector from them lvars ar = consvector(); ;;; Display in a loop, putting trailing period for i from 1 to length(ar) do printf(ar(i), '%s.'); endfor; printf('\n');
We could use list directly for printing:
for i in ls do printf(i, '%s.'); endfor;
so the convertion to vector is purely to satisfy task formulation.
Python
Interpreter: Python 2.5
words = "Hello,How,Are,You,Today" list_of_words = words.split(',') print '.'.join(list_of_words)
If you want to print each word on its own line:
for word in list_of_words: print word
or
print "\n".join(list_of_words)
Ruby
string = "Hello,How,Are,You,Today".split(',') string.each do |w| print "#{w}." end
Seed7
var array string: tokens is 0 times "";
tokens := split("Hello,How,Are,You,Today", ",");
Standard ML
val splitter = String.tokens (fn c => c = #","); val main = (String.concatWith ".") o splitter;
Test:
- main "Hello,How,Are,You,Today" val it = "Hello.How.Are.You.Today" : string
Tcl
Generating a list form a string by splitting on a comma:
split string ,
Joining the elements of a list by a period:
join list .
Thus the whole thing would look like this:
puts [join [split "Hello,How,Are,You,Today" ,] .]
If you'd like to retain the list in a variable with the name "words", it would only be marginally more complex:
puts [join [set words [split "Hello,How,Are,You,Today" ,]] .]