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String comparison with foreach loop. The expected output is "Facebook"

How can we compare two elements in a string and display the most repeated value using the foreach loop?
class Program
{
static void Main(string[] args)
{
string[] values = { "Facebook", "Google", "Facebook" };
foreach (var value in values)
{
// need to comparing the elements in the array
Console.WriteLine(value); /* print the repeated value*/
}
}
}

You could do this pretty easily with LINQ
var mostRepeatedValue = values
.GroupBy(v => v)
.OrderByDescending(gp => gp.Count())
.Select(g => g.Key).FirstOrDefault();

You can try below Code
Dictionary<string, int> stringOccurDict = new Dictionary<string, int>();
string[] values = { "Facebook", "Google", "Facebook" };
foreach(string x in values)
{
if (!stringOccurDict .ContainsKey(x))
stringOccur.Add(x, values.Count(c => values.Contains(c)));
});
string repeatedString = stringOccur.Where(x => x.Value == stringOccur.Values.Max()).FirstOrDefault().Key;
Output
Facebook
You can also get count by using .Value

How to find the duplicates in the given string in c#

I want to find the duplicates for a given string, I tried for collections, It is working fine, but i don't know how to do it for a string.
Here is the code I tried for collections,
string name = "this is a a program program";
string[] arr = name.Split(' ');
var myList = new List<string>();
var duplicates = new List<string>();
foreach(string res in arr)
{
if (!myList.Contains(res))
{
myList.Add(res);
}
else
{
duplicates.Add(res);
}
}
foreach(string result in duplicates)
{
Console.WriteLine(result);
}
Console.ReadLine();
But I want to find the duplicates for the below string and to store it in an array. How to do that?
eg:- string aa = "elements";
In the above string i want to find the duplicate characters and store it in an array
Can anyone help me?

Linq solution:
string name = "this is a a program program";
String[] result = name.Split(' ')
.GroupBy(word => word)
.Where(chunk => chunk.Count() > 1)
.Select(chunk => chunk.Key)
.ToArray();
Console.Write(String.Join(Environment.NewLine, result));
The same princicple for duplicate characters within a string:
String source = "elements";
Char[] result = source
.GroupBy(c => c)
.Where(chunk => chunk.Count() > 1)
.Select(chunk => chunk.Key)
.ToArray();
// result = ['e']
Console.Write(String.Join(Environment.NewLine, result));

string name = "elements";
var myList = new List<char>();
var duplicates = new List<char>();
foreach (char res in name)
{
if (!myList.Contains(res))
{
myList.Add(res);
}
else if (!duplicates.Contains(res))
{
duplicates.Add(res);
}
}
foreach (char result in duplicates)
{
Console.WriteLine(result);
}
Console.ReadLine();

string is an array of chars. So, you can use your collection approach.
But, I would reccomend typed HashSet. Just load it with string and you'll get array of chars without duplicates, with preserved order.
take a look:
string s = "aaabbcdaaee";
HashSet<char> hash = new HashSet<char>(s);
HashSet<char> hashDup = new HashSet<char>();
foreach (var c in s)
if (hash.Contains(c))
hash.Remove(c);
else
hashDup.Add(c);
foreach (var x in hashDup)
Console.WriteLine(x);
Console.ReadKey();

Instead of a List<> i'd use a HashSet<> because it doesn't allow duplicates and Add returns false in that case. It's more efficient. I'd also use a Dictionary<TKey,Tvalue> instead of the list to track the count of each char:
string text = "elements";
var duplicates = new HashSet<char>();
var duplicateCounts = new Dictionary<char, int>();
foreach (char c in text)
{
int charCount = 0;
bool isDuplicate = duplicateCounts.TryGetValue(c, out charCount);
duplicateCounts[c] = ++charCount;
if (isDuplicate)
duplicates.Add(c);
}
Now you have all unique duplicate chars in the HashSet and the count of each unique char in the dictionary. In this example the set only contains e because it's three times in the string.
So you could output it in the following way:
foreach(char dup in duplicates)
Console.WriteLine("Duplicate char {0} appears {1} times in the text."
, dup
, duplicateCounts[dup]);
For what it's worth, here's a LINQ one-liner which also creates a Dictionary that only contains the duplicate chars and their count:
Dictionary<char, int> duplicateCounts = text
.GroupBy(c => c)
.Where(g => g.Count() > 1)
.ToDictionary(g => g.Key, g => g.Count());
I've shown it as second approach because you should first understand the standard way.

string name = "this is a a program program";
var arr = name.Split(' ').ToArray();
var dup = arr.Where(p => arr.Count(q => q == p) > 1).Select(p => p);
HashSet<string> hash = new HashSet<string>(dup);
string duplicate = string.Join(" ", hash);

You can do this through `LINQ
string name = "this is a a program program";
var d = name.Split(' ').GroupBy(x => x).Select(y => new { word = y.Key, Wordcount = y.Count() }).Where(z=>z.cou > 1).ToList();

Use LINQ to group values:
public static IEnumerable<T> GetDuplicates<T>(this IEnumerable<T> list)
{
return list.GroupBy(item => item).SelectMany(group => group.Skip(1));
}
public static bool HasDuplicates<T>(this IEnumerable<T> list)
{
return list.GetDuplicates().IsNotEmpty();
}
Then you use these extensions like this:
var list = new List<string> { "a", "b", "b", "c" };
var duplicatedValues = list.GetDuplicates();

Convert a delimited string to a dictionary<string,string>

I have a string in the format
=key1=value1=key2=value2=key3=value3
I need to convert it to a Dictionary<string,string> for the above mentioned key value pairs.
What would be the best way to go about this?
I've tried this:
var input = "key1=value1=key2=value2=key3=value3";
var dict = Regex.Matches(input , #"\s*(.*?)\s*=\s*(.*?)\s*(=|$)")
.OfType<Match>()
.ToDictionary(m => m.Groups[1].Value, m => m.Groups[2].Value);

This can be accomplished with a little Linq:
"=key1=value1=key2=value2=key3=value3"
.Split('=') // Split into an array of strings
.Skip(1) // Skip the first (empty) value
.Select((v, i) => new { v, i }) // Get value and index
.GroupBy(x => x.i / 2) // Group every pair together
.ToDictionary(g => g.First().v, // First item in group is the key
g => g.Last().v) // Last item in group is the value

var dict = new Dictionary<string,string>();
var input = str.Split(new [] { '=' },StringSplitOptions.RemoveEmptyEntries);
for(int i=0; i<input.Length; i+=2)
{
dict.Add(input[i], input[i+1]);
}

parsing string and create Dictionary

I have the following string pattern: 1:2,2:3.
This is like array in one string:
The first element is: 1:2
The second element is: 2:3
I want to parse it and create a dictionary:
1,2 // 0 element in Dictionary
2,3 // 1 element in Dictionary
This is my code:
Dictionary<int,int> placesTypes = new Dictionary<int, int>();
foreach (var place in places.Split(','))
{
var keyValuePair = place.Split(':');
placesTypes.Add(int.Parse(keyValuePair[0]), int.Parse(keyValuePair[1]));
}
Is there the best way to do this?
Thanks.

You could change it to this:
var d = s.Split(',')
.Select(x => x.Split(':'))
.ToDictionary(x => int.Parse(x[0]), x => int.Parse(x[1]));

Dictionary<int, int> dict = "1:2,2:3".Split(',')
.Select(x => x.Split(':'))
.ToDictionary(x => int.Parse(x[0]),
x => int.Parse(x[1]));

var result = input.Split(new[]{','})
.Select(s => s.Split(new[]{':'}))
.ToDictionary(k => int.Parse(k[0]), v=> int.Parse(v[1]));
Live example: http://rextester.com/GTKO60478

If you're using C# >= 3.5 the ToDictionary LINQ method is the way to go:
var dictionary = places.Split(',')
.Select(place => place.Split(':'))
.ToDictionary(keyValue => int.Parse(keyValue[0]), keyValue => int.Parse(keyValue[1]));
Failing that, the following should suffice:
public static Dictionary<string, string> ToDictionary(string value, char pairSeperator, char valueSeperator)
{
Dictionary<int, int> dictionary = new Dictionary<int, int>();
foreach (string pair in value.Split(pairSeperator))
{
string[] keyValue = pair.Split(valueSeperator);
dictionary.Add(keyValue[0], keyValue[1]);
}
return dictionary;
}

Splitting only once, using MoreLinq.Batch
Dictionary<int, int> dict = places.Split(',', ':').Batch(2).Select(x=>x.ToArray()).ToDictionary(x=>int.Parse(x[0]),x=>int.Parse(x[1]));

How to split string into a dictionary

I have this string
string sx="(colorIndex=3)(font.family=Helvetica)(font.bold=1)";
and am splitting it with
string [] ss=sx.Split(new char[] { '(', ')' },
StringSplitOptions.RemoveEmptyEntries);
Instead of that, how could I split the result into a Dictionary<string,string>? The
resulting dictionary should look like:
Key Value
colorIndex 3
font.family Helvetica
font.bold 1

It can be done using LINQ ToDictionary() extension method:
string s1 = "(colorIndex=3)(font.family=Helvicta)(font.bold=1)";
string[] t = s1.Split(new[] { '(', ')' }, StringSplitOptions.RemoveEmptyEntries);
Dictionary<string, string> dictionary =
t.ToDictionary(s => s.Split('=')[0], s => s.Split('=')[1]);
EDIT: The same result can be achieved without splitting twice:
Dictionary<string, string> dictionary =
t.Select(item => item.Split('=')).ToDictionary(s => s[0], s => s[1]);

There may be more efficient ways, but this should work:
string sx = "(colorIndex=3)(font.family=Helvicta)(font.bold=1)";
var items = sx.Split(new[] { '(', ')' }, StringSplitOptions.RemoveEmptyEntries)
.Select(s => s.Split(new[] { '=' }));
Dictionary<string, string> dict = new Dictionary<string, string>();
foreach (var item in items)
{
dict.Add(item[0], item[1]);
}

Randal Schwartz has a rule of thumb: use split when you know what you want to throw away or regular expressions when you know what you want to keep.
You know what you want to keep:
string sx="(colorIndex=3)(font.family=Helvetica)(font.bold=1)";
Regex pattern = new Regex(#"\((?<name>.+?)=(?<value>.+?)\)");
var d = new Dictionary<string,string>();
foreach (Match m in pattern.Matches(sx))
d.Add(m.Groups["name"].Value, m.Groups["value"].Value);
With a little effort, you can do it with ToDictionary:
var d = Enumerable.ToDictionary(
Enumerable.Cast<Match>(pattern.Matches(sx)),
m => m.Groups["name"].Value,
m => m.Groups["value"].Value);
Not sure whether this looks nicer:
var d = Enumerable.Cast<Match>(pattern.Matches(sx)).
ToDictionary(m => m.Groups["name"].Value,
m => m.Groups["value"].Value);

string sx = "(colorIndex=3)(font.family=Helvetica)(font.bold=1)";
var dict = sx.Split(new[] { '(', ')' }, StringSplitOptions.RemoveEmptyEntries)
.Select(x => x.Split('='))
.ToDictionary(x => x[0], y => y[1]);

var dict = (from x in s1.Split(new[] { '(', ')' }, StringSplitOptions.RemoveEmptyEntries)
select new { s = x.Split('=') }).ToDictionary(x => x[0], x => x[1]);

Often used for http query splitting.
Usage: Dictionary<string, string> dict = stringToDictionary("userid=abc&password=xyz&retain=false");
public static Dictionary<string, string> stringToDictionary(string line, char stringSplit = '&', char keyValueSplit = '=')
{
return line.Split(new[] { stringSplit }, StringSplitOptions.RemoveEmptyEntries).Select(s => s.Split(new[] { keyValueSplit })).ToDictionary(x => x[0], y => y[1]); ;
}

You can try
string sx = "(colorIndex=3)(font.family=Helvetica)(font.bold=1)";
var keyValuePairs = sx.Split(new[] { '(', ')' }, StringSplitOptions.RemoveEmptyEntries)
.Select(v => v.Split('='))
.ToDictionary(v => v.First(), v => v.Last());

You could do this with regular expressions:
string sx = "(colorIndex=3)(font.family=Helvetica)(font.bold=1)";
Dictionary<string,string> dic = new Dictionary<string,string>();
Regex re = new Regex(#"\(([^=]+)=([^=]+)\)");
foreach(Match m in re.Matches(sx))
{
dic.Add(m.Groups[1].Value, m.Groups[2].Value);
}
// extract values, to prove correctness of function
foreach(var s in dic)
Console.WriteLine("{0}={1}", s.Key, s.Value);

I am just putting this here for reference...
For ASP.net, if you want to parse a string from the client side into a dictionary this is handy...
Create a JSON string on the client side either like this:
var args = "{'A':'1','B':'2','C':'" + varForC + "'}";
or like this:
var args = JSON.stringify(new { 'A':1, 'B':2, 'C':varForC});
or even like this:
var obj = {};
obj.A = 1;
obj.B = 2;
obj.C = varForC;
var args = JSON.stringify(obj);
pass it to the server...
then parse it on the server side like this:
JavaScriptSerializer jss = new JavaScriptSerializer();
Dictionary<String, String> dict = jss.Deserialize<Dictionary<String, String>>(args);
JavaScriptSerializer requires System.Web.Script.Serialization.