Friday Programming Quiz [modified]
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Here is my answer in C#. I couldnt find List<>.Intersect() anywhere on MSDN
public string GetIntersection(string csvString1, string csvString2) { string[] stringAry1 = csvString1.Split(new char[] { ',' }); List stringList = new List(); foreach (string str in stringAry1) { if (csvString2.Contains(str)) { stringList.Add(str); } } return String.Join(",", stringList.ToArray()); }sorry about the formatting. My browser is Opera -
Here is my answer in C#. I couldnt find List<>.Intersect() anywhere on MSDN
public string GetIntersection(string csvString1, string csvString2) { string[] stringAry1 = csvString1.Split(new char[] { ',' }); List stringList = new List(); foreach (string str in stringAry1) { if (csvString2.Contains(str)) { stringList.Add(str); } } return String.Join(",", stringList.ToArray()); }sorry about the formatting. My browser is OperaJ.Doli wrote:
I couldnt find List<>.Intersect() anywhere on MSDN
It's not there yet. You only get List<T>.Intersect() if you install the LINQ CTPs.
Oh geez... the forum keeps spinning... you'll take care o f it i'm sure, c'ause ... yeah, i neede this. *cough* anyway good job finding the bug.
-Shog9 on...a Firefox bug. -
Your code will return false positives if csvString1 has element "hi" and csvString2 has element "hide".
thanks for pointing that out. Here is my next try. public string GetIntersection(string csvString1, string csvString2) { List stringList = new List(csvString2.Split(new char[] { ',' })); List results = new List(); foreach (string str in csvString1.Split(new char[] { ',' })) { if (stringList.Contains(str)) { results.Add(str); } } return String.Join(",", results.ToArray()); } I dont like it that much, i just keep thinking that there is a better way.
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David Stone wrote:
list1.Intersect(list2).ToString();
I wonder whether that will work?
Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it. -Brian Kernighan
It won't. Also, my string splitting is wrong. I've modified it with the correct answer.
Oh geez... the forum keeps spinning... you'll take care o f it i'm sure, c'ause ... yeah, i neede this. *cough* anyway good job finding the bug.
-Shog9 on...a Firefox bug. -
While you are waiting for a build that crashes or may be not. Here is a simple programming problem (not question). The objective is to write the following function:
string GetIntersection(string csvString1, string csvString2) {
}
csvString1andcsvString2both contain comma separated list of unique values. The values can be in any order and they don't contain commas. The objective is to return a new CSV string which contains value from both the lists. e.g. csvString1: cat,rat,dog,lion csvString2: lion,elephant,mouse,tiger,rat,dog output: lion,rat,dog The coolest implementation of the function I have seen, so far, happens to be in JavaScript. Feel free to use any library functions. -- modified at 15:18 Friday 27th October, 2006
Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it. -Brian Kernighan
Sue me, I am lazy and uncreative right now. StringBuilder sb = new StringBuilder(); Hashtable table = new Hashtable(); string[] splitList = csvString1.Split(new char[]{','}); foreach(string s in splitList){ table[s] = s; } splitList = csvString2.Split(new char[]{','}); foreach(string s in splitList){ table[s] = s; } foreach(string s in table.Values){ sb.Append(s); } return sb.ToString();
On two occasions I have been asked [by members of Parliament], 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage
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Um. Yeah. That's too much. ;P
Mandrake, do you realize that in addition to fluoridating water, why, there are studies underway to fluoridate salt, flour, fruit juices, soup, sugar, milk, ice cream. Ice cream, Mandrake. Children's ice cream.
Yeah. You need to get a smaller monitor. Your team will thank you. BTW: "but at least it works" is a commonly used rationale (or excuse) for code that usually doesn't work very well at all. Remember, good code is about readability too. If it wasn't for that, we wouldn't keep source code after it was compiled once. Code is for people, not computers. All computers care about is the machine instructions.
Matt Gerrans
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While you are waiting for a build that crashes or may be not. Here is a simple programming problem (not question). The objective is to write the following function:
string GetIntersection(string csvString1, string csvString2) {
}
csvString1andcsvString2both contain comma separated list of unique values. The values can be in any order and they don't contain commas. The objective is to return a new CSV string which contains value from both the lists. e.g. csvString1: cat,rat,dog,lion csvString2: lion,elephant,mouse,tiger,rat,dog output: lion,rat,dog The coolest implementation of the function I have seen, so far, happens to be in JavaScript. Feel free to use any library functions. -- modified at 15:18 Friday 27th October, 2006
Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it. -Brian Kernighan
For the heck of it I threw together a C++ version. Note that the CMTrieIntT class is one of my own implementations of a trie and is extremely fast. (I have a case insensitive version that could also be used.)
int GetString(LPCTSTR& pStr) { while (*pStr == ',') pStr++; int len = 0; while (pStr[len] && pStr[len] != ',') len++; return len; } CString GetIntersection(LPCTSTR pStr1, LPCTSTR pStr2) { CMTrieIntT trie; for ( ; ; ) { int len = GetString(pStr1); if (len == 0) break; trie.Add(pStr1, 0, len); pStr1 += len; } CString rval; for ( ; ; ) { int len = GetString(pStr2); if (len == 0) break; if (trie.KeyExists(pStr2, len)) { if (rval.GetLength() > 0) rval += ','; rval.Append(pStr2, len); } pStr2 += len; } return rval; }Anyone who thinks he has a better idea of what's good for people than people do is a swine. - P.J. O'Rourke
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While you are waiting for a build that crashes or may be not. Here is a simple programming problem (not question). The objective is to write the following function:
string GetIntersection(string csvString1, string csvString2) {
}
csvString1andcsvString2both contain comma separated list of unique values. The values can be in any order and they don't contain commas. The objective is to return a new CSV string which contains value from both the lists. e.g. csvString1: cat,rat,dog,lion csvString2: lion,elephant,mouse,tiger,rat,dog output: lion,rat,dog The coolest implementation of the function I have seen, so far, happens to be in JavaScript. Feel free to use any library functions. -- modified at 15:18 Friday 27th October, 2006
Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it. -Brian Kernighan
my $l1 = "cat,rat,dog,lion"; my $l2 = "lion,elephant,mouse,tiger,rat,dog"; my (%h1,%h2); foreach(split ",", $l1) { $h1{$_}=$_;} foreach(split ",", $l2) { $h2{$_}=$_;} foreach( sort keys %h1 ) { if( $h2{$_} ) { print "$h1{$_}\n"; } } -
LINQ: (Note: Completely untested. I haven't set up Visual Studio on my new laptop yet. ;P Should work though.)
string GetCsvIntersection(string csv1, string csv2)
{
var list1 = new List<String>(Regex.Split(csv1, ","));
var list2 = new List<String>(Regex.Split(csv2, ","));var result = new StringBuilder(); foreach (string item in list1.Intersect(list2)) { result.AppendFormat("{0},", item); } return result.Remove(result.Length - 1, 1).ToString();}
Last modified: 2hrs 8mins after originally posted -- Yeah. Okay. LINQ still isn't as cool as Javascript
Oh geez... the forum keeps spinning... you'll take care o f it i'm sure, c'ause ... yeah, i neede this. *cough* anyway good job finding the bug. -Shog9 on...a Firefox bug.
Why use Regex.Split instead of just csv1.Split(',') ? Marc
People are just notoriously impossible. --DavidCrow
There's NO excuse for not commenting your code. -- John Simmons / outlaw programmer
People who say that they will refactor their code later to make it "good" don't understand refactoring, nor the art and craft of programming. -- Josh Smith -
Why use Regex.Split instead of just csv1.Split(',') ? Marc
People are just notoriously impossible. --DavidCrow
There's NO excuse for not commenting your code. -- John Simmons / outlaw programmer
People who say that they will refactor their code later to make it "good" don't understand refactoring, nor the art and craft of programming. -- Josh SmithBecause Regex.Split takes a String. String.Split needs a char array. And so I didn't want to construct a whole char[]. ;P There's no other good reason.
Mandrake, do you realize that in addition to fluoridating water, why, there are studies underway to fluoridate salt, flour, fruit juices, soup, sugar, milk, ice cream. Ice cream, Mandrake. Children's ice cream.
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Because Regex.Split takes a String. String.Split needs a char array. And so I didn't want to construct a whole char[]. ;P There's no other good reason.
Mandrake, do you realize that in addition to fluoridating water, why, there are studies underway to fluoridate salt, flour, fruit juices, soup, sugar, milk, ice cream. Ice cream, Mandrake. Children's ice cream.
David Stone wrote:
String.Split needs a char array.
Obviously, the documentation and Intellisense does not match the implementation, as:
string foo="a,b,c"; string\[\] foo2=foo.Split(',');Compiles fine. Unless there's some implicit conversion to char[]? I use the above syntax all the time! :~ Marc
People are just notoriously impossible. --DavidCrow
There's NO excuse for not commenting your code. -- John Simmons / outlaw programmer
People who say that they will refactor their code later to make it "good" don't understand refactoring, nor the art and craft of programming. -- Josh Smith -
David Stone wrote:
String.Split needs a char array.
Obviously, the documentation and Intellisense does not match the implementation, as:
string foo="a,b,c"; string\[\] foo2=foo.Split(',');Compiles fine. Unless there's some implicit conversion to char[]? I use the above syntax all the time! :~ Marc
People are just notoriously impossible. --DavidCrow
There's NO excuse for not commenting your code. -- John Simmons / outlaw programmer
People who say that they will refactor their code later to make it "good" don't understand refactoring, nor the art and craft of programming. -- Josh SmithWeird. Huh. Then there's really no reason (here) to use Regex.Split. Go figure.
Oh geez... the forum keeps spinning... you'll take care o f it i'm sure, c'ause ... yeah, i neede this. *cough* anyway good job finding the bug.
-Shog9 on...a Firefox bug.