## Saturday, April 26, 2014

### Using Predicate and Func in linq using c#

```//Creation of Predicate

Predicate<String> checkGreterthen5= x=> x.Length>5;

List<String> oLst=new List<string>();

String str = oLst.Find(checkGreterthen5);

Console.WriteLine(str);//Saurabh

//Creation of Func

delegate Double CalcAreaPointer(int r);

CalcAreaPointer _obj= r => 3.14 * r*r;

Double Area=_obj(5);

Func<double,double,double> _obj2=(r,e)=> 3.14 *r*e;

//Action<>

Double Area2 = _obj2(5,2);
```

### Most Occurred Number in Integer Array using Linq using C#

```String[] _numbers = { "2", "1", "3", "2", "4", "6", "2", "1", "4", "6", "6", "4", "8", "1", "3", "8" };
var _query2 = from n in _numbers
group n by n into g
select new
{
number = g.Key,
count = g.Count()
};
var _MaxCount = _query2.Max(a => a.count);
var mostOccurednumber = _query2
.Where(g => g.count == _MaxCount)
.Select(g => g.number);
```

## Friday, April 25, 2014

### Merging three array and take top 5 numbers using LINQ in C#

```int[] _inputs1 = { 11,12, 13, 14, 15, 16, 17, 18, 169 };
int[] _inputs2 = { 11, 22, 33, 24, 25, 56, 67, 88, 99 };
int[] _inputs3 = { 1, 2, 3, 4, 5, 6, 7, 68, 98 };
Int32[] Concatenate=Input1.Concat(Input2).Concat(Input3).OrderByDescending(a=>a)
.Take(5).ToArray();
foreach(int a in Concatenate)
{
Console.writeline(a);
}

//output {168,99,98,88,68}
```

### Reversing integer Array through LINQ in c#

```public Int32[] ReverseThroughLINQ(Int32[] _inputs,int k=0)
{
if (k==0) {
k=_inputs.Count();
}
int[] reverse = _inputs.Take(k).Reverse().ToArray();
int[] straight = _inputs.Skip(k).ToArray();
int[] _concatenatedString = reverse.Concat(straight).ToArray();
return _concatenatedString;
}
```

### use Contains in LINQ using C#

```var query6 = from n1 in names
select n1.ToUpper() into n2
where n1.Contains("a") // Illegal: n1 out of scope.
select n2;
//rewrite query number 6
var query10 = from n1 in names
let n2 = n1.ToUpper()
where n2.Contains("A")
select n1;
```

### Ordering generic list IEnumerable

```string[] musos = { "Roger Waters", "Rick Wright", "David Gilmour"};
IEnumerable query = musos.OrderBy(m => m.Split().Last());
Using Inner Query

string[] names = { "Tom", "Dick", "Harry", "Mary", "Jay", "Maya" };
var outerQuery = names
.Where(n => n.Length == names.OrderBy(n2 => n2.Length)
.Select(n2 => n2.Length).First()
); //output Tom,Jay

Same query as above

IEnumerable comprehension = from n in names
where n.Length == (from n2 in names
orderby n2.Length
select n;
IEnumerable query4 = names
.Select(n => Regex.Replace(n, "[aeiou]", ""))
.Where(n => n.Length > 2)
.OrderBy(n => n.Length);
IEnumerable query4 = names
.Select(n => Regex.Replace(n, "[aeiou]", ""))
.Where(n => n.Length > 2)
.OrderBy(n => n.Length);

Same as above query

IEnumerable query5 = from n in names
select Regex.Replace(n, "[aeiou]", "") into g
where g.Length > 2
select n2.Length).First()
orderby g.Length
select g;

IEnumerable query8 = from n1 in
(
from n2 in names
select Regex.Replace(n2, "[aeiou]", "")
)
where n1.Length > 2
orderby n1
select n1;

IEnumerable query9 = from n in names
let vowelless = Regex.Replace(n, "[aeiou]", "")
where vowelless.Length > 2
orderby vowelless
select n; // Thanks to let, n is still in scope.
```

### using First, FirstOrDefault, DefaultIfEmpty, Single, SingleOrDefault

```string[] names = { "Tom", "Dick", "Harry", "Mary", "Jay", "Maya" };
int[] number = { 1, 5, 6, 8, 20, 15, 34, 67, 98, 12, 23 };
var num = number.Where(n => n > 100).FirstOrDefault(); //num=0
var numm = number.Where(n => n > 100).First(); //will give an error
var nummm = number.Where(n => n > 100).DefaultIfEmpty(1).First(); //nummm=1
var nam = names.Where(n => n.StartsWith("z")).FirstOrDefault();//nam=null
var name = names.Where(n => n.StartsWith("M")).SingleOrDefault();
//will give an error because two values found with “M”
```

### Find Customer list whom city exists in city array

```String[] _cities = { "London", "New Delhi" };

var _customers = new[] { new { Name = "Saurabh", City = "London" },
new { Name = "Sumit", City = "New Delhi" },
new { Name = "Rohit", City = "London" },
new { Name = "Rahul", City = "Mumbai" },
new { Name = "Suresh", City = "London" },
new { Name = "Sunil", City = "New Delhi" },
new { Name = "Mahesh", City = "Agra" }
};

var _query = from c in _customers
where (_cities).Contains(c.City)
select c;
```
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