什么是使用IQueryable在LINQ的背景下？
它是用于开发扩展方法还是任何其他目的？
如何使用Linq从每个组中选择Top值
当我有一个代码段,如:
var teams = new Team[]
{
new Team{PlayerName="Ricky",TeamName="Australia", PlayerScore=234},
new Team{PlayerName="Hussy",TeamName="Australia", PlayerScore=134},
new Team{PlayerName="Clark",TeamName="Australia", PlayerScore=334},
new Team{PlayerName="Sankakara",TeamName="SriLanka", PlayerScore=34},
new Team{PlayerName="Udana",TeamName="SriLanka", PlayerScore=56},
new Team{PlayerName="Jayasurya",TeamName="SriLanka", PlayerScore=433},
new Team{PlayerName="Flintop",TeamName="England", PlayerScore=111},
new Team{PlayerName="Hamirson",TeamName="England", PlayerScore=13},
new Team{PlayerName="Colingwood",TeamName="England", PlayerScore=421}
};
期望的结果:
Team Name Player Name Score Srilanka Jayasurya 433 England colingwood 421 Australia Clark 334
请考虑以下代码:
string[] words =
{ "Too", "much", "of", "anything", "is" ,"good","for","nothing"};
var groups =from word in words
orderby word ascending
group word by word.Length into lengthGroups
orderby lengthGroups.Key descending
select new {Length=lengthGroups.Key, Words=lengthGroups};
foreach (var group in groups)
{
Console.WriteLine("Words of length " + group.Length);
foreach (string word in group.Words)
Console.WriteLine(" " + word);
}
为什么我们在这里需要关键字"new"？.你能给出一些其他简单的例子来正确理解它吗？
在解决面试问题时
问题 当数字乘以2到9之间的整数时,需要以这种方式找到一个六位数字,当数字反转时给出原始的六位数字.
例:
假设我乘以219978*4我得到879912,当反向879912我将得到219978回来.
我用它解决了
for (long l = 100000; l < 999999; l++)
{
var num = l.ToString();
for (int i = 3; i < 9; i++)
{
var mul = l * i;
string str = mul.ToString();
char[] splitDigits = str.ToCharArray();
string reversedDigit =
new string(splitDigits.Reverse().ToArray());
if (reversedDigit.CompareTo(num) == 0)
{
Console.WriteLine("{0} * {1}= {2},
when multiplied {3} ", num, i, mul,reversedDigit);
}
}
}
最初的任务是使用linq解决它.例如,我在处理临时计算时有点困惑
当我使用
var = from l in Enumerable.Range(100000,999999)
from i in …请告诉我(1)中"where"和(2)中"where()"之间的区别.
何时使用"where"和"where()"？
List<Person> pList =
new List<Person>
{
new Person
{EmpNo=1,FirstName="Marc",LastName="Loel",Salary=3434},
new Person
{EmpNo=2, FirstName="Steve",LastName="Kaith",Salary=4545},
new Person
{EmpNo=3,FirstName="Neol",LastName="Henk",Salary=2222},
};
(1) var v = from p in pList where p.EmpNo == 1 select new { p.FirstName };
(2) var query =pList .Where(p => p.EmpNo == 1)
.Select(p => new { p.FirstName});
如何在化合物选择过程中将两个数组合并到一个数组中(不使用Union)(问题在访谈时提出).
var num1 = new int[] { 12, 3, 4, 5 };
var num2 = new int[] { 1, 33, 6, 10 };
我试过了
var pairs = from a in num1 from b in num2 select new {combined={a,b}};
预期:合并需要{12,3,4,5,1,33,6,10}
这也是我最近面临的一个面试问题.
说明:
任务是100美元(请考虑一些货币)将给我.我需要购买三个项目项目A,项目B,项目C.成本(我不确定0.25美元或0.75美元是有意义的,所以认为其他货币)itemA = 0.25 $,itemB = 0.75 $和itemC = 20 $.我需要以100美元的价格购买100件商品(我可以购买任意数量的itemA,itemB,ItemC但总数应为100).
解决方案: 使用for循环我解决了它.
for (int i = 1; i <= 100; i++)
{
for (int j = 1; j <= 100; j++)
{
for (int k = 1; k <= 20; k++)
{
if ((i * 0.25) + (j * 0.75) + (k * 5) == 100 && (i+j+k)==100)
{
Console.WriteLine("item1={0},item2={1},item3={2}", i, j, k);
}
}
}
}
我也得到了结果.
item1=1 , item2=93,item3=6 // cost =100,items=100
item1=18,item2=74,item3=8 //cost=100,items=100 …首先,我要向Marc Gravel,Dahlbyk和其他人表示衷心的感谢,帮助我实际应用linq.
以下是我在面试中遇到的几个问题,以解决应用Linq问题.因为我不熟悉Linq,所以我在不使用Linq的情况下解决了它.
我很欣赏能帮助我使用Linq解决问题的答案
提前致谢.
3,5,7,11,13或17.
为了确保没有任何矛盾,假设三个数字是a,b和c.然后,没有数字的组合:
说abc,acb,bac,bca,cab和cba将除以3,5,7,11,13或17.
示例:
当我拿248时,它的任何组合(284,428,482,842,824)都不会被3,5,7,11,13或17整除.
public void FindingRareNumbers()
{
for (int i = 1; i <= 9; i++)
{
for (int j = 1; j <= 9; j++)
{
for (int k = 1; k <= 9; k++)
{
//to form the three digit
string digit = i.ToString() + j.ToString() + k.ToString();
//converting to integer
int StrToDigit = Convert.ToInt32(digit);
char[] digitcombination = digit.ToCharArray();
string PossibleCombination = …当我宣布
object o = new { name = "Bruce",Age=21 };
Console.WriteLine("name={0},age={1}",???,??? );
现在我如何打印姓名和年龄的价值？
int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };
string[] strings = { "zero", "one", "two", "three", "four", "five", "six",
"seven","eight", "nine" };
var textNums =
from n in numbers
select strings[n];
Console.WriteLine("Number strings:");
foreach (var s in textNums)
{
Console.WriteLine(s);
}
1)将"整数"转换为表示"word"中的整数的机制是什么？
2)像int这样的转换只能用int到string吗？或者我们可以通过这种转变来玩乐吗？
我尝试了一些代码来获得"运行总计"和"小计",但这确实产生了成功的结果.
当给出代码时:
var salesPeople =
new SalesPerson[]
{
new SalesPerson{Name="Ricky", RegionCode="R001",SalesAmount=100,
SalesDate=Convert.ToDateTime("01/Jan/2009")},
new SalesPerson{Name="Mark", RegionCode="R001",SalesAmount=200,
SalesDate=Convert.ToDateTime("02/Jan/2009")},
new SalesPerson{Name="Jon", RegionCode="R001",SalesAmount=400,
SalesDate=Convert.ToDateTime("10/Jan/2009")},
new SalesPerson{Name="Ricky", RegionCode="R001",SalesAmount=100,
SalesDate=Convert.ToDateTime("05/Jan/2009")},
new SalesPerson{Name="Mark", RegionCode="R001",SalesAmount=200,
SalesDate=Convert.ToDateTime("07/Jan/2009")},
new SalesPerson{Name="Jon", RegionCode="R001",SalesAmount=250,
SalesDate=Convert.ToDateTime("11/Jan/2009")},
new SalesPerson{Name="Ricky", RegionCode="R002",SalesAmount=50,
SalesDate=Convert.ToDateTime("01/feb/2009")},
new SalesPerson{Name="Mark", RegionCode="R002",SalesAmount=120,
SalesDate=Convert.ToDateTime("02/feb/2009")},
new SalesPerson{Name="Peter", RegionCode="R002",SalesAmount=30,
SalesDate=Convert.ToDateTime("10/feb/2009")},
new SalesPerson{Name="Ricky", RegionCode="R002",SalesAmount=400,
SalesDate=Convert.ToDateTime("05/feb/2009")},
new SalesPerson{Name="Mark", RegionCode="R002",SalesAmount=70,
SalesDate=Convert.ToDateTime("07/feb/2009")},
new SalesPerson{Name="Peter", RegionCode="R002",SalesAmount=60,
SalesDate=Convert.ToDateTime("11/feb/2009")}
};
如何找到与以下类似的Total,SubTotal,RunningTotal.
(1) Running Total Based on Region and Month
Sales History
-------------------------------------------------------------
Region Code Name MonthyRunningTotal SalesDate
(By Month)
-------------------------------------------------------------
R001 Ricky 100 …