Develop Reference

changing string dynamically in C#

When I'm putting the following code specifically in the immediate window in Visual studio, it returns correctly:
whatToMatch.Remove((whatToMatch.IndexOf(input[i])), 1)
But when I put it in a program as shown below, it fails:-
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace IsPangram
{
class Program
{
static void Main(string[] args)
{
string whatToMatch = "abcdefghijklmnopqrstuvwxyz";
string input = Console.ReadLine().ToLower();
for (int i = 0; i < input.Length; i++)
{
if (whatToMatch.Contains(input[i]))
{
whatToMatch.Remove((whatToMatch.IndexOf(input[i])), 1);
}
if (whatToMatch.Length == 0)
Console.WriteLine("pangram");
}
Console.WriteLine("not pangram");
}
}
}
I was expecting "whatToMatch" to change dynamically as it is correct code, but it's not changing. Why? And how to resolve this issue?

From msdn about String.Remove Method (Int32, Int32)
It returns a new string in which a specified number of characters in
the current instance beginning at a specified position have been
deleted.
So it doesn't modify the string that call it, it return a new string.
So you should use
whatToMatch = whatToMatch.Remove((whatToMatch.IndexOf(input[i])), 1)

As already mentioned, strings in .NET are immutable, therefore you cannot expect your string to change dynamically.
Here is a concise solution to your problem using LINQ:
using System;
using System.Collections.Generic;
using System.Linq;
namespace IsPangram
{
static class Program
{
public static bool IsPangram(this string input)
{
return
!input.ToLower()
.Aggregate("abcdefghijklmnopqrstuvwxyz".ToList(),
(ts, c) => ts.Where(x => x != c).ToList())
.Any();
}
public static void Main(string[] args)
{
Console.WriteLine(Console.ReadLine().IsPangram() ?
"Is pangram" :
"Is not pangram");
}
}
}

C#-Error-does not contain a constructor that takes 1 arguments-I don't get what I am doing wrong?

I keep trying to make this C# program work, but I keep getting an Error about the constructor taking 1 argument. I don't get it. I think it has to do with the " Test myTest = new Test(3);" but I don't know what to do with it.
Any help or steering me in the right direction would be greatly appreciated. Thank you.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication1
{
public class Test
{
private int tally;
public void Test(int start)
{
tally = start;
}
public void AddFive()
{
tally += 5;
}
public void Display()
{
Console.WriteLine("The tally is {0}", tally);
}
public void Main(string[] args)
{
Test myTest = new Test(3);
myTest.AddFive();
myTest.Display ();
}
}
}

Constructors don't have return type.
So instead of
public void Test(int start)
{
tally = start;
}
you should have
public Test(int start)
{
tally = start;
}

In the constructor definition you said to return void. That is not required. Your constrctor should be
public Test(int strat)
{
...
}

C# help, can't get list of names from 4 loops

Im trying to learn the 4 types of loops, for, foreach, while and do. I've made this code so far:
Loops.cs:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace LoopFrame
{
class Loops
{
// attribute (not property)
private List<string> names;
// constructor
public Loops()
{
// initilize
names = new List<string>();
//insert values
names.Add("Peter");
names.Add("Susanne");
names.Add("Steen");
names.Add("Mohammed");
names.Add("Poul");
names.Add("Ebbe");
names.Add("Henrik");
names.Add("Per");
names.Add("Anders");
names.Add("Lars");
names.Add("Vibeke");
names.Add("Mogens");
names.Add("Michael");
}
//
// 4 loop methods
//
// all should print out the whole list 'names'
//
public void WhileLoop()
{
int x = 0;
while (x < names.Count)
{
Console.WriteLine(names[++x]);
}
}
public void DoWhileLoop()
{
int x = 0;
do
{
Console.WriteLine(names[++x]);
x++;
} while (x < names.Count);
}
public void ForLoop()
{
for (int x = 0; x < 0; x++)
{
Console.WriteLine(names[++x]);
}
}
public void ForeachLoop()
{
int[] names = new int[] { 0 };
foreach (int element in names)
{
System.Console.WriteLine(element);
}
System.Console.WriteLine();
}
}
}
Program.cs:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace LoopFrame
{
class Program
{
static void Main(string[] args)
{
Loops loops = new Loops();
Console.WriteLine();
Console.ReadLine();
}
}
}
I think there is some faults, but the program can currently compile, but it just makes a black screen.
Thank you for your time.

As it stands, you're constructing the Loops instance, but you've not called any methods.
static void Main(string[] args)
{
Loops loops = new Loops();
loops.WhileLoop();
loops.DoWhileLoop();
loops.ForLoop();
loops.ForeachLoop();
Console.WriteLine();
Console.ReadLine();
}
You may want to read up on Methods.
As an aside, you can populate your list with much less code:
names = new List<string> { "Peter", "Suzanne", "Steen" ... };
As another aside, in two of your loop methods, you're incrementing the index variable twice per iteration, which should only print out every other element.

You are not calling any method that should print the list content.
Add:
static void Main(string[] args)
{
Loops loops = new Loops();
//Call methods
loops.WhileLoop();
loops.DoWhileLoop();
//...
Console.WriteLine();
Console.ReadLine();
}

Your foreach will not work. As you declared a new names as int[]. To make your foreach workable with declared list. You should use
foreach(string s in names)
{
Console.WriteLine("Name is : "+s);
}

Error missing namespace or assembly reference

I am writing the code right, but getting error - missing namespace or assembly reference.Is there something wrong with the code or I am missing something?
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication5
{
class Program
{
static void Main(string[] args)
{
int i = 0;
int sum = 0;
int[] arr = new int[] { 1, 2 };
do
{
{
sum += arr[1];
Console.WriteLine("Wow");
i++;
}
}
while (i < 3);
}
}
}
Error is : Error Cannot initialize type 'int' with a collection initializer because it does not implement 'System.Collections.IEnumerable

My namespace ended in Console (i.e. MyProject.Console) which messed up the calls to Console.Write. In this case, either write the fully qualified name System.Console.Write or change the namespace.

i am writing the code right
Don't start with this assumption. Always start with the assumption that the compiler is correct, and your code is wrong.
You haven't shown any using directives. In this case all you need is
using System;
(Either at the very top of your code or within the namespace declaration.)
or change your WriteLine call to:
System.Console.WriteLine("Wow");
If that doesn't fix it (or if you've already got such a using directive but forgot to include it), then your project is probably somewhat broken - it's not like you're using any exotic types.

Import the System namespace or just use System.Console.WriteLine("...");
using System;
namespace TestNs
{
public class Test
{
static void Main()
{
Console.WriteLine("Hello World");
}
}
}

I faced a similar problem. The namespace name I used ended with .Console, so there was a conflict with System.Console
using System;
namespace Test.Console
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Hello World!");
}
}
}
I changed Test.Console to Test.ConsoleApp, and problem fixed for me
using System;
namespace Test.ConsoleApp
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Hello World!");
}
}
}

The minimum for your console app should have this
using System;
using System.Collections.Generic;
using System.Text;
namespace TestConsole
{
class Program
{
static void Main(string[] args)
{
}
}
}

thanks to all for help i managed to solve the problem with the help of you guys :)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication5
{
class Program
{
static void Main(string[] args)
{
int i = 0; //initialize integer i=0
int sum = 0; // initialize integer sum = 0;
int[] arr = new int[]{1, 2, 3, 4}; // array containing 4 integers elements
do
{
{
sum+=arr[i]; //sum each integer in array and store it in var sum
i++; //increment i for each element of array
Console.WriteLine(sum); //output the var sum conatining values after each increment
}
}
while(i<=3); //check condition for number of elements in array
}
}
}

Using a namespace of Myproject.App also causes problems, in the same way as MyProject.Console (as per contactmatt's answer, above).

IronRuby and C#, Execute File

Why this work:
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using Microsoft.Scripting;
using Microsoft.Scripting.Hosting;
using IronRuby;
class Tutorial
{
static void Main(string[] args)
{
var engine = Ruby.CreateEngine();
engine.Runtime.Globals.SetVariable("Holly",new Holly("Test"));
engine.Execute("Holly.Say");
Console.ReadLine();
}
}
class Holly
{
string speech;
public Holly(string speech)
{
this.speech = speech;
}
public void Say()
{
Console.WriteLine("Hollu said " + this.speech);
}
}
and this is not work
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using Microsoft.Scripting;
using Microsoft.Scripting.Hosting;
using IronRuby;
class Tutorial
{
static void Main(string[] args)
{
var engine = Ruby.CreateEngine();
engine.Runtime.Globals.SetVariable("Mouse",new Holly("Test"));
engine.ExecuteFile("./test.rb");
Console.ReadLine();
}
}
class Holly
{
string speech;
public Holly(string speech)
{
this.speech = speech;
}
public void Say()
{
Console.WriteLine("Hollu said " + this.speech);
}
}

Try this
engine.ExecuteFile(#"..\test.rb");
Also wrap your code in try/catch statement and check for exception
try
{
var engine = Ruby.CreateEngine();
engine.Runtime.Globals.SetVariable("Holly",new Holly("Test"));
engine.ExecuteFile(#"..\test.rb");
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}