Check for specific character between two characters - c#

To illustrate:
Take the input string "Yesterday I ate two bu rgers" (space intentional)
I want to check the input string to see if a space (or any other pre-defined character) " " exists between the two characters (in this case) "u" and "r". And if it exists delete this character.
First I came up with this:
string someString = "Yesterday I ate two bu rgers";
string charA = 'u', charB = 'r';
if (someString.Contains(charA) &&
someString.Substring(someString.IndexOf(charA) + 1).Equals(" ") &&
someString.Substring(someString.IndexOf(charA) + 2).Equals(charB))
//delete the space
However not only does this feel (and look) inefficient as heck, It also fails if the sentence would be "Yesterday you ate two bu rgers" since it will take the index of the first "u". So I would have to do an additional check for multiple instances of charA
Another solution I thought of is to split the sentence on every space, and see if the last character of the split matches charA and the first character of the next split matches charB. And if it does join the two together.
string[] splitString = someString.Split(null);
for (int i = 0; i < splitString.Length -1; i++)
{
string lastChar = splitString[i].Substring(splitString[i].Length - 1);
string firstChar = splitString[i + 1].Substring(0, 1);
if(lastChar.Equals(charA) && firstChar.Equals(charB))
{
string joined = splitString[i] + splitString[i + 1];
}
}
However this method is also flawed as it breaks when i.e two spaces are present in the input.
Is there a way to do this without needing a bunch of if statements or loops? (unless there really is no other way I would really like to not use regex)

A string is an array of characters. Loop through it and inspect the characters.
for (int i = 2; i < someString.Length; i++) {
if (someString[i] == charB && someString[i - 2] == charA) {
//TODO: delete the char in between.
break;
}
}
If you start at index = 2 and test for the second character, you can simply go back by 2 positions to inspect the first one.
But of course you could also look ahead like this:
for (int i = 0; i < someString.Length - 2; i++) {
if (someString[i] == charA && someString[i + 2] == charB) {
//TODO: delete the char in between.
break;
}
}

Related

Missing characters after string concatenate

I am having a problem whereby the letter at the position(e.g 39) would be replaced with the text I wanted to input. However what I want was to insert the text at position 39 instead of replacing it. Anyone please guide me on this.
string description = variables[1]["value"].ToString();// where I get the text
int nInterval = 39;// for every 39 characters in the text I would have a newline
string res = String.Concat(description.Select((c, z) => z > 0 && (z % nInterval) == 0 ? Environment.NewLine +"Hello"+(((z/ nInterval)*18)+83).ToString()+"world": c.ToString()));
file_lines = file_lines.Replace("<<<terms_conditions>>>",resterms); //file_lines is where I read the text file
Original text
Present this redemption slip to receive: One
After String.Concat
Present this redemption slip to receive\r\n\u001bHello101world
One //: is gone
I am also having a issue where I want to put a new line if it contains * in the text. If anybody is able to help that would be great.
Edit:
What I want to achieve is something like this
Input
*Item is considered paid if unsealed.*No replacement or compensation will be given for any expired coupons.
so like i need to find every 39 character and also * to input newline so it will be
Output
*Item is considered paid if unsealed.
*No replacement or compensation will be
given for any expired coupons.
Try String.Insert(Int32, String) Method
Insert \n where you need new line.
If I understood your question properly, you want a newline after every 39 characters. You can use string.Insert(Int32, String) method for that.
And use String.Replace(String, String) for your * problem.
Below code snippet doing that using a simple for loop.
string sampleStr = "Lorem Ipsum* is simply..";
for (int i = 39; i < sampleStr.Length; i = i + 39){
sampleStr = sampleStr.Insert(i, Environment.NewLine);
}
//sampleStr = sampleStr.Replace("*", Environment.NewLine);
int[] indexes = Enumerable.Range(0, sampleStr.Length).Where(x => sampleStr[x] == '*').ToArray();
for (int i = 0; i < indexes.Length; i++)
{
int position = indexes[i];
if (position > 0) sampleStr = sampleStr.Insert(position, Environment.NewLine);
}
If you want to do both together
int[] indexes = Enumerable.Range(0, sampleStr.Length).Where(x => sampleStr[x] == '*' || x % 39 == 0).ToArray();
int j = 0;
foreach (var position in indexes)
{
if (position > 0)
{
sampleStr = sampleStr.Insert(position + j, Environment.NewLine);
j = j + 2; // increment by two since newline will take two chars
}
}
Without debating the method chosen to achieve the desired result, the problem with the code is that at the 39th character it adds some text, but the character itself has been forgotten.
Changing the following line should give the expected output.
string res = String.Concat(description.Select((c, z) => z > 0 && (z % nInterval) == 0 ? Environment.NewLine + "Hello" + (((z / nInterval) * 18) + 83).ToString() + "world" + c.ToString() : c.ToString()));
<== UPDATED ANSWER BASED ON CLARIFICATION IN QUESTION ==>
This will do what you want, I believe. See comments in line.
var description = "*Item is considered paid if unsealed.*No replacement or compensation will be given for any expired coupons.";
var nInterval = 39; // for every 39 characters in the text I would have a newline
var newline = "\r\n"; // for clarity in the Linq statement. Can be set to Environment.Newline if desired.
var z = 0; // we'll handle the count manually.
var res = string.Concat(
description.Select(
(c) => (++z == nInterval || c == '*') // increment z and check if we've hit the boundary OR if we've hit a *
&& ((z = 0)==0) // resetting the count - this only happens if the first condition was true
? newline + (c == ' ' ? string.Empty : c.ToString()) // if the first character of a newline is a space, we don't need it
: c.ToString()
));
Output:
*Item is considered paid if unsealed.
*No replacement or compensation will be
given for any expired coupons.

How to remove certain characters

I'm trying to remove single vowels from a string, but not if a vowel is double same.
For example string
"I am keeping a foobar"
should print out as
"m keepng foobr"
I have tried everything but didn't come up with a solution so far.
Try:
Regex.Replace(input, #"([aeiou])\1", "");
Though for I am keeping a foobar, it will give you m keepng foobr, which is different to your required m keepng foobr, as you're stripped spaces out of your required result, too.
If you want to remove the extraneous spaces, then it's a three step operation: remove vowels; remove proceeding/trailing spaces; remove double spaces.
var raw = Regex.Replace(input, #"([aeiou])\1", "");
var trimmed = raw.Trim();
var final = trimmed.Replace(" ", " ");
You could try this logic:
loop trough string and check two by two characters
if (isBothVowelsAndEqual()) do nothing; else removeFirstChar();
EDIT:
public List<char> vowels = "AEIOUaeiou".ToList();
public bool isBothVowelsAndEqual(char first, char second)
{
return (first == second && vowels.Contains(first));
}
const string s = "I am keeeping a foobar";
string output=String.Empty;
for (int i = 0; i < s.Length-1; i++)
{
if (isBothVowelsAndEqual(s[i], s[i + 1]))
{
output = output + s[i] + s[i+1];
i++;
}
else
{
if (!vowels.Contains(s[i])) {
output += s[i];
}
}
}
Console.WriteLine(output.Trim());

Upper Case Everything Before the nth character in .NET

I need to capitalize everything before the second - from the beginning of the string in .NET. What is the best way to do this? The string before the second dash can be anything. I need a new single string once this is complete.
Before
Tt-Fga - Louisville - Kentucky
After
TT-FGA - Louisville - Kentucky
This should get the job done for your specific case:
public static string ToUpperUntilSecondHyphen(string text)
{
int index = text.IndexOf('-', text.IndexOf('-') + 1);
return text.Substring(0, index).ToUpper() + text.Substring(index);
}
A more generalized method could look something like this:
public static string ToUpperUntilNthOccurrenceOfChar(string text, char c, int occurrences)
{
if (occurrences > text.Count(x => x == c))
{
return text.ToUpper();
}
int index = 0;
for (int i = 0; i < occurrences; i++, index++)
{
index = text.IndexOf(c, index);
}
return text.Substring(0, index).ToUpper() + text.Substring(index);
}
Identify the location of the hyphen with IndexOf. You'll have to use this function twice so that you can find the first hyphen, and then the second one.
Construct the substring that only contains the characters up to that with Substring. Construct the substring that contains all the remaining characters as well.
Upper case the first string with ToUpper.
Concatenate with the + operator.
(.*?-.*)(?=-)
You can use replace here.Replace with $1.upper() or something which is available in c#.
See
http://regex101.com/r/yR3mM3/50
I went ahead and did this. If there is a better answer let me know.
var parts = #event.EventParent.Name.Split(new[] {'-'}, StringSplitOptions.RemoveEmptyEntries);
for (int i = 0; i < parts.Length; i++)
{
if (i >= 2)
break;
parts[i] = parts[i].ToUpper();
}
#event.EventParent.Name = string.Join("-", parts);

Special characters Regex

Hello I'm try to remove special characters from user inputs.
public void fd()
{
string output = "";
string input = Console.ReadLine();
char[] charArray = input.ToCharArray();
foreach (var item in charArray)
{
if (!Char.IsLetterOrDigit(item))
{
\\\CODE HERE }
}
output = new string(trimmedChars);
Console.WriteLine(output);
}
At the end I'm turning it back to a string. My code only removes one special character in the string. Does anyone have any suggestions on a easier way instead
You have a nice implementation, just consider using next code, which is only a bit shorter, but has a little bit higher abstractions
var input = " th#ere's! ";
Func<char, bool> isSpecialChar = ch => !char.IsLetter(ch) && !char.IsDigit(ch);
for (int i = 1; i < input.Length - 1; i++)
{
//if current character is a special symbol
if(isSpecialChar(input[i]))
{
//if previous or next character are special symbols
if(isSpecialChar(input[i-1]) || isSpecialChar(input[i+1]))
{
//remove that character
input = input.Remove(i, 1);
//decrease counter, since we removed one char
i--;
}
}
}
Console.WriteLine(input); //prints " th#ere's "
A new string would be created each time you would call Remove. Use a StringBuilder for a more memory-performant solution.
The problem with your code is that you are taking the data from charArray and putting the result in trimmedChars for each change that you make, so each change will ignore all previous changes and work with the original. At the end you only have the last change.
Another problem with the code is that you are using IndexOf to get the index of a character, but that will get the index of the first occurance of that character, not the index where you got that character. For example when you are at the second ! in the string "foo!bar!" you will get the index of the first one.
You don't need to turn the string into an array to work with the characters in the string. You can just loop through the index of the characters in the string.
Note that you should also check the value of the index when you are looking at the characters before and after, so that you don't try to look at characters that are outside the string.
public void fd() {
string input = Console.ReadLine();
int index = 0;
while (index < input.Length) {
if (!Char.IsLetterOrDigit(input, index) && ((index == 0 || !Char.IsLetterOrDigit(input, index - 1)) || (index == input.Length - 1 || !Char.IsLetterOrDigit(input, index + 1)))) {
input = input.Remove(index, 1);
} else {
index++;
}
}
Console.WriteLine(input);
}
Been awhile since I've hit on C#, but a reg ex might be helpful
string input = string.Format("{0}! ", Console.ReadLine());
Regex rgx = new Regex("(?i:[^a-z]?)[.](?i:[^a-z]?)");
string output = rgx.Replace(input, "$1$2");
The regex looks for a character with a non-alpha character on left or right and replaces it with nothing.

What is the most efficient way to detect if a string contains a number of consecutive duplicate characters in C#?

For example, a user entered "I love this post!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
the consecutive duplicate exclamation mark "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!" should be detected.
The following regular expression would detect repeating chars. You could up the number or limit this to specific characters to make it more robust.
int threshold = 3;
string stringToMatch = "thisstringrepeatsss";
string pattern = "(\\d)\\" + threshold + " + ";
Regex r = new Regex(pattern);
Match m = r.Match(stringToMatch);
while(m.Success)
{
Console.WriteLine("character passes threshold " + m.ToString());
m = m.NextMatch();
}
Here's and example of a function that searches for a sequence of consecutive chars of a specified length and also ignores white space characters:
public static bool HasConsecutiveChars(string source, int sequenceLength)
{
if (string.IsNullOrEmpty(source))
return false;
if (source.Length == 1)
return false;
int charCount = 1;
for (int i = 0; i < source.Length - 1; i++)
{
char c = source[i];
if (Char.IsWhiteSpace(c))
continue;
if (c == source[i+1])
{
charCount++;
if (charCount >= sequenceLength)
return true;
}
else
charCount = 1;
}
return false;
}
Edit fixed range bug :/
Can be done in O(n) easily: for each character, if the previous character is the same as the current, increment a temporary count. If it's different, reset your temporary count. At each step, update your global if needed.
For abbccc you get:
a => temp = 1, global = 1
b => temp = 1, global = 1
b => temp = 2, global = 2
c => temp = 1, global = 2
c => temp = 2, global = 2
c => temp = 3, global = 3
=> c appears three times. Extend it to get the position, then you should be able to print the "ccc" substring.
You can extend this to give you the starting position fairly easily, I'll leave that to you.
Here is a quick solution I crafted with some extra duplicates thrown in for good measure. As others pointed out in the comments, some duplicates are going to be completely legitimate, so you may want to narrow your criteria to punctuation instead of mere characters.
string input = "I loove this post!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!aa";
int index = -1;
int count =1;
List<string> dupes = new List<string>();
for (int i = 0; i < input.Length-1; i++)
{
if (input[i] == input[i + 1])
{
if (index == -1)
index = i;
count++;
}
else if (index > -1)
{
dupes.Add(input.Substring(index, count));
index = -1;
count = 1;
}
}
if (index > -1)
{
dupes.Add(input.Substring(index, count));
}
The better way i my opinion is create a array, each element in array is responsible for one character pair on string next to each other, eg first aa, bb, cc, dd. This array construct with 0 on each element.
Solve of this problem is a for on this string and update array values.
You can next analyze this array for what you want.
Example: For string: bbaaaccccdab, your result array would be { 2, 1, 3 }, because 'aa' can find 2 times, 'bb' can find one time (at start of string), 'cc' can find three times.
Why 'cc' three times? Because 'cc'cc & c'cc'c & cc'cc'.
Use LINQ! (For everything, not just this)
string test = "aabb";
return test.Where((item, index) => index > 0 && item.Equals(test.ElementAt(index)));
// returns "abb", where each of these items has the previous letter before it
OR
string test = "aabb";
return test.Where((item, index) => index > 0 && item.Equals(test.ElementAt(index))).Any();
// returns true

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