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I am unable to use substring. How can I fix this?

I am trying to see weather the string is in alphabetical order or no and this error pops up
System.ArgumentOutOfRangeException: Index and length must refer to a location within the string.
Parameter name: length
at System.String.Substring(Int32 startIndex, Int32 length)
at Rextester.Program.Main(String[] args)**
public static void Main(string[] args)
{
string str = "bat\ncat\ndog\n";
int c = 0;
for (int i = 0; i < str.Length; i++)
{
if ((str.Substring(i,i + 1).Equals("\n")))
{
c++;
}
}
String[] strArray = new String[c + 1]; //declare with size
int g = 0;
String h = "";
for (int i = 0; i < str.Length; i++)
{
if ((str.Substring(i,i + 1).Equals("\n")))
{
strArray[g] = h;
h = "";
g = g + 1;
}
else
{
h = h + str.Substring(i,i + 1);
}
}
String p = "True";
for (int i = 0; i < g; i++)
{
if (i < (g - 1))
{
String f = strArray[i];
String g2 = strArray[i + 1];
char d = f[0];
char s = g2[0];
int d1 = (int)d;
int s1 = (int)s;
if (d1 > s1)
{
p = "False";
}
}
}
Console.WriteLine(p);
}
}

Not sure about what you are doing in your second loop and why is it so complex. We can do the same like this. Hope this helps.
using System;
public class Program
{
public static void Main()
{
string str = "abcd";
str = str.Replace('\n',' ');
String p = "True";
for (int i = 1; i < str.Length; i++) {
// if element at index 'i' is less
// than the element at index 'i-1'
// then the string is not sorted
if (str[i] < str[i - 1]) {
p = "false";
}
}
Console.WriteLine(p);
}
}

Pay attention to the definition of substring
The substring starts at a specified character position and has a
specified length
Considering your first use of substring, here
for (int i = 0; i < str.Length; i++)
{
if (str.Substring(i, i + 1).Equals("\n"))
{
c++;
}
}
What happens when we get to i=6 here? Substring tries to give you a new string that starts at position i = 6, and is length = 7 characters long. So it tries to give you 7 characters starting from str[6] to str[12]. Well, there is no str[12], so you get an exception.
Its clear that your intent is NOT to get a string that starts at position 6 and is 7 characters long. You want ONE character, so your loop should be this
for (int i = 0; i < str.Length; i++)
{
if (str.Substring(i, 1).Equals("\n"))
{
c++;
}
}
But theres a much simpler way to get your words in alphabetical order using LINQ
string str = "bat\ncat\ndog\n";
//Removes the trailing \n so you don't have one entry that is only whitespace
str = str.Trim();
string[] strSplit = str.Split('\n').OrderBy(x => x[0]).ToArray();
Now all substrings are sorted alphabetically and you can do whatever you want with them

C# Hangman IndexOf Loop

I am a beginner in C# and i am trying to make a "hangman" game. I got stuck at the process when the player guess a letter.
If the word for example is DATA, the application only gets the first A in DATA.
I understand that i have to loop the word to get all the A´s but i am having touble with making it work!
here is my code for the method myGuess:
public void myGuess(String letter)
{
int plats = 0;
string wordToGuess = label4.Text;
plats = wordToGuess.IndexOf(letter);
string wordToShow = label5.Text;
//ersätt "_" med bokstaven på alla positioner bokstaven dyker upp
wordToShow = wordToShow.Substring(0, wordToGuess.IndexOf(letter)) + letter +
wordToShow.Substring(plats + 1, wordToShow.Length - (plats + 1));
label5.Text = wordToShow;
}
I have been trying to google it but because i am a beginner i don't understand the
suggestions people give. Hopefully it is a way to loop for more than one letter with IndexOf?

IndexOf returns the index of the first instance of the character in the string. You could manipulate your string using substring, but you'd be making it more complicated than you need to need. Instead, you can just loop through each of the characters in the String with a for loop:
for (int i = 0; i < wordToGuess.Length; i++ )
{
if (WordToGuess[i] == letter)
{
//Update the correctly guessed letters, (using value of i to determine which letter to make visible.)
}
}
label5.Text = wordToShow;

You can use this:
label4(wordToGuess): DATA
label5(wordToShow): ****
When you call myGuess('A')
label4(wordToGuess): DATA
label5(wordToShow): *A*A
When you call myGuess('T')
label4(wordToGuess): DATA
label5(wordToShow): *ATA
...
public void myGuess(char letter)
{
string wordToGuess = label4.Text;
string wordToShow = label5.Text;
if (wordToShow.Length == 0)
{
for (int i = 0; i < wordToGuess.Length; i++)
wordToShow += "*";
}
for (int i = 0; i < wordToGuess.Length; i++)
{
if (wordToGuess[i] == letter || wordToGuess[i] == wordToShow[i])
wordToShow = wordToShow.Remove(i,1).Insert(i, Char.ToString(letter));
}
label5.Text = wordToShow;
}

Here's a long solution that's probably overly generic.
List<int> findIndexes(string myStr, char letter)
{
var foundIndexes = new List<int>();
for (int i = 0; i < myStr.Length; i++)
{
if (myStr[i] == letter)
foundIndexes.Add(i);
}
return foundIndexes;
}
string ReplaceIndex(string s, int index, char letter){
return s.Substring(0, index )
+ letter
+ s.Substring(index + 1, s.Length - (index + 1));
}
void Main()
{
string s= "data";
string wordToShow = "____";
var letter = 'a';
var indexes = findIndexes(s, letter);
foreach (var index in indexes)
{
wordToShow = ReplaceIndex(wordToShow, index, letter);
}
Console.WriteLine (wordToShow);
}

A simple for loop should handle it.
for (int i = 0; i < wordToGuess.Length; i++)
{
if (wordToGuess[i].ToString().Equals(letter.ToString(), System.StringComparison.InvariantCultureIgnoreCase))
{
wordToShow = string.Format("{0}{1}{2}", wordToShow.Substring(0, i), letter, wordToShow.Substring(i, wordToShow.Length - (i + 1)));
}
}
Here's a fiddle: http://dotnetfiddle.net/UATeVJ

Number of loop recursions as a parameter

I'm building a list of strings that contains all permutations of 2-letter strings, for instance "aa" to "zz". This is what I have:
public List<string> SomeMethod(int NumberOfChars) {
for (var i = 0; i < 26; i++)
{
char character1 = (char)(i + 97);
var Letter1 = character1.ToString();
for (var j = 0; j < 26; j++)
{
char character2 = (char)(j + 97);
var Letter2 = character2.ToString();
string TheString = Letter1 + Letter2;
TheList.Add(TheString);
}
}
return TheList;
}
Basically, it's a loop inside a loop that combines characters from the alphabet. Now suppose I want to include NumberOfChars as a parameter that determines the length of each string. For instance, if I pass in 2 it would return all 676 2-letter strings from "aa" to "zz" and if I pass in 3 it would return all 17,576 3-letter strings from "aaa" to "zzz".
For the moment, the easiest way to do it would be to have two different methods, one that returns 2-letter strings with two nested loops and another one that returns 3-letter strings with 3 nested loops.
What's a cleaner way to do this?
Thanks.

How about a method like this:
public IEnumerable<string> SomeMethod(int NumberOfChars)
{
if (NumberOfChars == 0)
{
yield return string.Empty;
}
else
{
for (var i = 'a'; i <= 'z'; i++)
{
foreach (var s in SomeMethod(NumberOfChars - 1))
{
yield return i + s;
}
}
}
}
And just for fun, here's another solution using Linq:
public IEnumerable<string> SomeMethod(int n)
{
var r = Enumerable.Range('a', 26).Select(x => ((char)x).ToString());
return (n > 1) ? r.SelectMany(x => SomeMethod(n - 1), (x, y) => x + y) : r;
}

Here's an alternative that uses a loop instead of recursion:
public static List<string> SomeMethod(int numberOfChars)
{
IEnumerable<string> results = new List<string> { "" };
for (int i = 0; i < numberOfChars; ++i)
results = from s in results
from c in Enumerable.Range('a', 26)
select s + (char)c;
return results.ToList();
}

Frequency of Characters in visual c# windows form application

I am developing a program in visual c# windows form application.
I need to find out the number of characters in a text box and display each characters' frequency in a list box. I have the following code:
private void btnCheckFrequency_Click(object sender, EventArgs e)
{
lstFreqMeter.Items.Clear();
string str;
int c = 1;
int strlen;
str = txtString.Text;
strlen = txtString.TextLength;
int[] counter = new int[strlen];
for (int i = 0; i < strlen; i++)
{
for (int j = i + 1; j < strlen; j++)
{
if (str[i] == str[j])
{
c += 1;
}
}
counter[i] = c;
c = 1;
}
for (int k = 0; k < counter.Length; k++)
{
lstFreqMeter.Items.Add(counter[k]);
}
}
In this code when I click the "Check Frequency" button the program gives, as output, the frequency of each character and repeated characters, and also spaces which we do not want.

3 loops to accomplish this is where you are going wrong. I think you are trying to make it too complicated.
Its frowned upon to give answers to homework questions, but some hints as to direction should help.
Declare a Dictionary<char, int>
Make only one loop. For each char in your string.
Inside the loop, populate a Dictionary<char, int> with your results.
If the char exists in the dictionary, set the int to int++, if not, add the char to the dictionary with int of 1.
Outside the loop, AddRange to your lstFreqMeter.Items.

You can get the number of chars in a string by using Count on the string.
Getting the frequency of each char you can iterate through the string and increment an integer. A dictionary (key/value list) would be a great datatype to hold this data.
const string textString = "aaabbbcccaaattteeevvvooo";
var numberOfChars = textString.Count();
var dictionary = new Dictionary<char,int>();
foreach (var letter in textString)
{
if (dictionary.ContainsKey(letter))
dictionary[letter]++;
else
dictionary[letter] = 1;
}
The Dictionary will contain a key (the char) and a value (the count).

Try something like this:
var letters = Enumerable.Range('A', 26).Select(i => (char)i);
var sourceChars = letters.Concat(myString.ToUpperInvariant());
var results = from c in sourceChars
group c by c into g
where char.IsLetter(g.Key)
orderby g.Key
select new { Char = g.Key, Count = g.Count() - 1 };
foreach (var result in results)
{
Console.WriteLine("There are {0} {1}'s.", result.Count, result.Char);
}
This will return you a class of how many times each letter appears in myString

Maintain a dictionary of the matched characters and increment each character count as it is matched.
Dictionary<char, int> count = new Dictionary<char,int>();
string str = textString.Text;
int len = str.Length;
for(int i = 0; i < len; i ++)
{
if (str[i] == ' ') continue;
if (count.ContainsKey(str[i]))
{
count[str[i]] += 1;
} else {
count.Add(str[i], 1);
}
}
foreach(char key in count.Keys)
{
Console.WriteLine("{0} : {1}", key, count[key]);
}

Counting how many times a certain char appears in a string before any other char appears

I have many strings. Each string is prepended with at least 1 $. What is the best way to loop through the chars of each string to count how many $'s there are per string.
eg:
"$hello" - 1
"$$hello" - 2
"$$h$ello" - 2

You could use the Count method
var count = mystring.Count(x => x == '$')

int count = myString.TakeWhile(c => c == '$').Count();
And without LINQ
int count = 0;
while(count < myString.Length && myString[count] == '$') count++;

The simplest approach would be to use LINQ:
var count = text.TakeWhile(c => c == '$').Count();
There are certainly more efficient approaches, but that's probably the simplest.

You could do this, it doesn't require LINQ, but it's not the best way to do it(since you make split the whole string and put it in an array and just pick the length of it, you could better just do a while loop and check every character), but it works.
int count = test.Split('$').Length - 1;

var str ="hello";
str.Where(c => c == 'l').Count() // 2

int count = yourText.Length - yourText.TrimStart('$').Length;

int count = Regex.Matches(myString,"$").Count;

public static int GetHowManyTimeOccurenceCharInString(string text, char c)
{
int count = 0;
foreach(char ch in text)
{
if(ch.Equals(c))
{
count++;
}
}
return count;
}

just a simple answer:
public static int CountChars(string myString, char myChar)
{
int count = 0;
for (int i = 0; i < myString.Length; i++)
{
if (myString[i] == myChar) ++count;
}
return count;
}
Cheers! - Rick

One approach you could take is the following method:
// Counts how many of a certain character occurs in the given string
public static int CharCountInString(char chr, string str)
{
return str.Split(chr).Length-1;
}
As per the parameters this method returns the count of a specific character within a specific string.
This method works by splitting the string into an array by the specified character and then returning the length of that array -1.

//This code worked for me
class CountOfLettersOfString
{
static void Main()
{
Console.WriteLine("Enter string to check count of letters");
string name = Console.ReadLine();
//Method1
char[] testedalphabets = new char[26];
int[] letterCount = new int[26];
int countTestesd = 0;
Console.WriteLine($"Given String is:{name}");
for (int i = 0; i < name.Length - 1; i++)
{
int countChar = 1;
bool isCharTested = false;
for (int j = 0; j < testedalphabets.Length - 1; j++)
{
if (name[i] == testedalphabets[j])
{
isCharTested = true;
break;
}
}
if (!isCharTested)
{
testedalphabets[countTestesd] = name[i];
for (int k = i + 1; k < name.Length - 1; k++)
{
if (name[i] == name[k])
{
countChar++;
}
}
letterCount[countTestesd] = countChar;
countTestesd++;
}
else
{
continue;
}
}
for (int i = 0; i < testedalphabets.Length - 1; i++)
{
if (!char.IsLetter(testedalphabets[i]))
{
continue;
}
Console.WriteLine($"{testedalphabets[i]}-{letterCount[i]}");
}
//Method2
var g = from c in name.ToLower().ToCharArray() // make sure that L and l are the same eg
group c by c into m
select new { Key = m.Key, Count = m.Count() };
foreach (var item in g)
{
Console.WriteLine(string.Format("Character:{0} Appears {1} times", item.Key.ToString(), item.Count));
}
Console.ReadLine();
}
}

This is a similar Solution to find how many email addresses included in a string. This way is more efficient`
int count = 0;
foreach (char c in email.Trim())
if (c == '#') count++;