I am building an e-mail validation program.
How can I check if my E-Mail has 3 letters before the # and 2 letters after the "." I tried else if but it didn't work.
string rightPassword = "red#gmx.to";
string enter = Console.ReadLine();
string red = rightPassword.Substring(0, 3);
string to = rightPassword.Substring(8);
int lengthRed = red.Length;
int lengthTo = to.Length;
do
{
Console.Write("Write the E-Mail: ");
enter = Console.ReadLine();
if (rightPassword == enter)
{
Console.WriteLine("Right Password");
}
else if (lengthRed < 3 ) // I have to check if it has 3 letters before the #//
{
Console.WriteLine("You need 3 letters before the #")
}
else if (lengthTo < 2)
{
Console.WriteLine("You need 2 letter after the ".")
}
} while (enter != "enter");
Just use Regular expressions for pattern matching.
You should use this regex to achieve what you want: ^\w{3}#\w+.\w{2}$
code example:
string email = "abc#aa.co";
Regex regex = new Regex(#"^\w{3}#\w+.\w{2}$");
Match match = regex.Match(email);
if(match.Success)
Console.WriteLine("Email matches pattern");
else Console.WriteLine("Email does not matches pattern");
If you don't want to use Regular Expressions, even though it is highly encouraged, you can add a method:
public static bool HasValidUsername(string email)
{
for (int i = 0; i < 3; i++)
{
if (!email[i].IsLetter())
{
return false;
}
}
return true;
}
And use the method in your code:
else if (!HasValidUsername(enter))
{
Console.WriteLine("You need 3 letters before the #");
}
But keep in mind, that the example above will not validate numbers or symbols. You could use email[i].IsSymbol() or email[i].IsNumber() to check for that.
Note:
x#com is a valid email adress for a domain registrar. That said, most of them use a subdomain for their email. x#x.com for example. Handling all real world email cases is not as trivial as it might seem.
Using Char.IsLetter() method
public bool IsValidEmail(string email)
{
return email.Length > 2 Char.IsLetter(str[0]) && Char.IsLetter(str[1]) && Char.IsLetter(str[2]);
}
You could also use Split.
Something like
string red = rightPassword.Split('#')[0];
string to = rightPassword.Split('.').Last();
you'll also be able to check what's after the "#" if you use
string red = rightPassword.Split('#')[0];
string gmx= rightPassword.Split('#')[1];
string to = rightPassword.Split('.').Last();
I'm working on a project for college and it's Yearbook project. I need to put years in exact format yyyy/yyyy (eg. 2020/2021) can anyone help me to parse and make a validation?
I know that you have probably found an answer already, the code is for anyone in the future that may have the same issue.
You won't make use of a date picker, but rather a list of dropdowns showing the different sessions.
Check the code below
//subtract the current year from two years to start from the previous year
var currentYear = DateTime.Now.Year - 2;
List<string> allsessions = new List<string>();
//loop for the next five years
for (int i = 0; i < 5; i++)
{
//add curent year by one to get the next year
var nextYear = currentYear + 1;
var label = $"{currentYear}/{nextYear}";
//add data to list
allsessions.Add(label);
currentYear = nextYear;
}
Console.WriteLine("All Sessions: \n"+string.Join(", ", allsessions));
Console.ReadLine();
// output will be:
// All Sessions:
// 2021/2022, 2022/2023, 2023/2024, 2024/2025, 2025/2026
bool CheckDateYear(string s)
{
string s1 = s.Split('/')[0];//s.Split('-')[0]
string s2 = s.Split('/')[1];
if (DateTime.Now.Year.ToString() != s2 || (DateTime.Now.Year - 1).ToString() != s1)
return false;
else
return true;
}
...
if(CheckDateYear("2020/2021")
{
...
}
You can use regex to validate:
using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string[] values= { "2020/2021", "2019-2020",
"199e-2000" };
Regex rgx = new Regex(#"^\d{4}(/\d{4})"); // 4 digits, forward slash, 4 digits
foreach (string value in values)
Console.WriteLine("{0} {1} a valid entry.",
value,
rgx.IsMatch(value) ? "is" : "is not");
}
}
// The example displays the following output:
// 2020/2021 is a valid entry.
// 2019-2020 is not a valid entry.
// 199e-2000 is not a valid entry.
I'm making a program that reverses a string and doesn't allow for anything else than letters and whitespaces, problem is that if i enter a non-valid input and then try to input a valid input it just keeps printing error. I think the problem has something to do with my while loop and the bool result, but i can't figure it out. Please help and thank you!
static void Reverse()
{
string name;
Console.Write("Enter your name: ");
name = Console.ReadLine();
bool result = name.All(c => char.IsWhiteSpace(c) || char.IsLetter(c));
if (Regex.IsMatch(name, #"^[a-zA-Z- ]+$")) // Validates the input for characters and/or spaces
{
char[] charArr = name.ToCharArray();
Array.Reverse(charArr);
string nameRev = new string(charArr);
Console.WriteLine("String is {0}", nameRev);
}
else
{
while (name == String.Empty || result == false) //Should validate the input for whitespace or letter if it doesn't pass the first validation
{
Console.Write("Error! Enter your name, only letters allowed: ");
name = Console.ReadLine();
}
}
You need to wrap your while loop around the hole sequence instead of just having it inside the else statement.
Example:
static void Reverse()
{
// Continues executing as long as result stays false.
bool result;
do
{
string name;
Console.Write("Enter your name: ");
name = Console.ReadLine();
result = name.All(c => char.IsWhiteSpace(c) || char.IsLetter(c));
if (Regex.IsMatch(name, #"^[a-zA-Z- ]+$"))
{
char[] charArr = name.ToCharArray();
Array.Reverse(charArr);
string nameRev = new string(charArr);
Console.WriteLine("String is {0}", nameRev);
}
else
{
Console.WriteLine("Error! Only letters allowed");
}
}
while (!result);
}
Hi so im trying to validate my string here so that it does not allow any input that starts with: "911" so if you type: "9 11", "91 1", "9 1 1" it should go through my if statement. It works with "911" but not the others, here's my code:
using System;
using System.Collections.Generic;
namespace Phone_List
{
class Program
{
static void Main(string[] args)
{
var phoneList = new List<string>();
string input;
Console.WriteLine("Input: ");
while ((input = Console.ReadLine()) != "")
{
phoneList.Add(input);
for (int i = 0; i < phoneList.Count; i++)
{
if (phoneList[i].Substring(0, 3) == "911")
{
input.StartsWith("9 11");
input.StartsWith("9 1 1");
input.StartsWith("91 1");
Console.WriteLine("NO");
Console.ReadLine();
return;
}
else
{
Console.WriteLine("YES");
Console.ReadLine();
return;
}
}
}
}
}
}
As you can see I am trying to use "input.StartsWith("9 11");" but it does not work...
You could use the Replace method of String; the condition you describe can be formulated as follows.
input.Replace(" ", "").StartsWith("911")
Use regular expressions for checks like this.
For example:
Regex.IsMatch(input, "^\\s*9\\s*1\\s*1");
This regex matches all strings that include whitespaces in front of and between "911".
Use the following to check if the string starts with "911":
First create a copy from the input string but without any white spaces:
string input_without_white_spaces =
new string(input.ToCharArray().Where(x => !char.IsWhiteSpace(x)).ToArray());
Then you can check if the string starts with 911 like this:
if (input_without_white_spaces.StartsWith("911"))
{
...
}
bool valid = s.StartsWith("911") ||
!string.Join("",s.Split()).StartsWith("911");
I have some strings containing code for emoji icons, like :grinning:, :kissing_heart:, or :bouquet:. I'd like to process them to remove the emoji codes.
For example, given:
Hello:grinning: , how are you?:kissing_heart: Are you fine?:bouquet:
I want to get this:
Hello , how are you? Are you fine?
I know I can use this code:
richTextBox2.Text = richTextBox1.Text.Replace(":kissing_heart:", "").Replace(":bouquet:", "").Replace(":grinning:", "").ToString();
However, there are 856 different emoji icons I have to remove (which, using this method, would take 856 calls to Replace()). Is there any other way to accomplish this?
You can use Regex to match the word between :anything:. Using Replace with function you can make other validation.
string pattern = #":(.*?):";
string input = "Hello:grinning: , how are you?:kissing_heart: Are you fine?:bouquet: Are you super fan, for example. :words not to replace:";
string output = Regex.Replace(input, pattern, (m) =>
{
if (m.ToString().Split(' ').Count() > 1) // more than 1 word and other validations that will help preventing parsing the user text
{
return m.ToString();
}
return String.Empty;
}); // "Hello , how are you? Are you fine? Are you super fan, for example. :words not to replace:"
If you don't want to use Replace that make use of a lambda expression, you can use \w, as #yorye-nathan mentioned, to match only words.
string pattern = #":(\w*):";
string input = "Hello:grinning: , how are you?:kissing_heart: Are you fine?:bouquet: Are you super fan, for example. :words not to replace:";
string output = Regex.Replace(input, pattern, String.Empty); // "Hello , how are you? Are you fine? Are you super fan, for example. :words not to replace:"
string Text = "Hello:grinning: , how are you?:kissing_heart: Are you fine?:bouquet:";
i would solve it that way
List<string> Emoj = new List<string>() { ":kissing_heart:", ":bouquet:", ":grinning:" };
Emoj.ForEach(x => Text = Text.Replace(x, string.Empty));
UPDATE - refering to Detail's Comment
Another approach: replace only existing Emojs
List<string> Emoj = new List<string>() { ":kissing_heart:", ":bouquet:", ":grinning:" };
var Matches = Regex.Matches(Text, #":(\w*):").Cast<Match>().Select(x => x.Value);
Emoj.Intersect(Matches).ToList().ForEach(x => Text = Text.Replace(x, string.Empty));
But i'm not sure if it's that big difference for such short chat-strings and it's more important to have code that's easy to read/maintain. OP's question was about reducing redundancy Text.Replace().Text.Replace() and not about the most efficient solution.
I would use a combination of some of the techniques already suggested. Firstly, I'd store the 800+ emoji strings in a database and then load them up at runtime. Use a HashSet to store these in memory, so that we have a O(1) lookup time (very fast). Use Regex to pull out all potential pattern matches from the input and then compare each to our hashed emoji, removing the valid ones and leaving any non-emoji patterns the user has entered themselves...
public class Program
{
//hashset for in memory representation of emoji,
//lookups are O(1), so very fast
private HashSet<string> _emoji = null;
public Program(IEnumerable<string> emojiFromDb)
{
//load emoji from datastore (db/file,etc)
//into memory at startup
_emoji = new HashSet<string>(emojiFromDb);
}
public string RemoveEmoji(string input)
{
//pattern to search for
string pattern = #":(\w*):";
string output = input;
//use regex to find all potential patterns in the input
MatchCollection matches = Regex.Matches(input, pattern);
//only do this if we actually find the
//pattern in the input string...
if (matches.Count > 0)
{
//refine this to a distinct list of unique patterns
IEnumerable<string> distinct =
matches.Cast<Match>().Select(m => m.Value).Distinct();
//then check each one against the hashset, only removing
//registered emoji. This allows non-emoji versions
//of the pattern to survive...
foreach (string match in distinct)
if (_emoji.Contains(match))
output = output.Replace(match, string.Empty);
}
return output;
}
}
public class MainClass
{
static void Main(string[] args)
{
var program = new Program(new string[] { ":grinning:", ":kissing_heart:", ":bouquet:" });
string output = program.RemoveEmoji("Hello:grinning: :imadethis:, how are you?:kissing_heart: Are you fine?:bouquet: This is:a:strange:thing :to type:, but valid :nonetheless:");
Console.WriteLine(output);
}
}
Which results in:
Hello :imadethis:, how are you? Are you fine? This is:a:strange:thing :to type:,
but valid :nonetheless:
You do not have to replace all 856 emoji's. You only have to replace those that appear in the string. So have a look at:
Finding a substring using C# with a twist
Basically you extract all tokens ie the strings between : and : and then replace those with string.Empty()
If you are concerned that the search will return strings that are not emojis such as :some other text: then you could have a hash table lookup to make sure that replacing said found token is appropriate to do.
Finally got around to write something up. I'm combining a couple previously mentioned ideas, with the fact we should only loop over the string once. Based on those requirement, this sound like the perfect job for Linq.
You should probably cache the HashSet. Other than that, this has O(n) performance and only goes over the list once. Would be interesting to benchmark, but this could very well be the most efficient solution.
The approach is pretty straight forwards.
First load all Emoij in a HashSet so we can quickly look them up.
Split the string with input.Split(':') at the :.
Decide if we keep the current element.
If the last element was a match, keep the current element.
If the last element was no match, check if the current element matches.
If it does, ignore it. (This effectively removes the substring from the output).
If it doesn't, append : back and keep it.
Rebuild our string with a StringBuilder.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication1
{
static class Program
{
static void Main(string[] args)
{
ISet<string> emojiList = new HashSet<string>(new[] { "kissing_heart", "bouquet", "grinning" });
Console.WriteLine("Hello:grinning: , ho:w: a::re you?:kissing_heart:kissing_heart: Are you fine?:bouquet:".RemoveEmoji(':', emojiList));
Console.ReadLine();
}
public static string RemoveEmoji(this string input, char delimiter, ISet<string> emojiList)
{
StringBuilder sb = new StringBuilder();
input.Split(delimiter).Aggregate(true, (prev, curr) =>
{
if (prev)
{
sb.Append(curr);
return false;
}
if (emojiList.Contains(curr))
{
return true;
}
sb.Append(delimiter);
sb.Append(curr);
return false;
});
return sb.ToString();
}
}
}
Edit: I did something cool using the Rx library, but then realized Aggregate is the IEnumerable counterpart of Scan in Rx, thus simplifying the code even more.
If efficiency is a concern and to avoid processing "false positives", consider rewriting the string using a StringBuilder while skipping the special emoji tokens:
static HashSet<string> emojis = new HashSet<string>()
{
"grinning",
"kissing_heart",
"bouquet"
};
static string RemoveEmojis(string input)
{
StringBuilder sb = new StringBuilder();
int length = input.Length;
int startIndex = 0;
int colonIndex = input.IndexOf(':');
while (colonIndex >= 0 && startIndex < length)
{
//Keep normal text
int substringLength = colonIndex - startIndex;
if (substringLength > 0)
sb.Append(input.Substring(startIndex, substringLength));
//Advance the feed and get the next colon
startIndex = colonIndex + 1;
colonIndex = input.IndexOf(':', startIndex);
if (colonIndex < 0) //No more colons, so no more emojis
{
//Don't forget that first colon we found
sb.Append(':');
//Add the rest of the text
sb.Append(input.Substring(startIndex));
break;
}
else //Possible emoji, let's check
{
string token = input.Substring(startIndex, colonIndex - startIndex);
if (emojis.Contains(token)) //It's a match, so we skip this text
{
//Advance the feed
startIndex = colonIndex + 1;
colonIndex = input.IndexOf(':', startIndex);
}
else //No match, so we keep the normal text
{
//Don't forget the colon
sb.Append(':');
//Instead of doing another substring next loop, let's just use the one we already have
sb.Append(token);
startIndex = colonIndex;
}
}
}
return sb.ToString();
}
static void Main(string[] args)
{
List<string> inputs = new List<string>()
{
"Hello:grinning: , how are you?:kissing_heart: Are you fine?:bouquet:",
"Tricky test:123:grinning:",
"Hello:grinning: :imadethis:, how are you?:kissing_heart: Are you fine?:bouquet: This is:a:strange:thing :to type:, but valid :nonetheless:"
};
foreach (string input in inputs)
{
Console.WriteLine("In <- " + input);
Console.WriteLine("Out -> " + RemoveEmojis(input));
Console.WriteLine();
}
Console.WriteLine("\r\n\r\nPress enter to exit...");
Console.ReadLine();
}
Outputs:
In <- Hello:grinning: , how are you?:kissing_heart: Are you fine?:bouquet:
Out -> Hello , how are you? Are you fine?
In <- Tricky test:123:grinning:
Out -> Tricky test:123
In <- Hello:grinning: :imadethis:, how are you?:kissing_heart: Are you fine?:bouquet: This is:a:strange:thing :to type:, but valid :nonetheless:
Out -> Hello :imadethis:, how are you? Are you fine? This is:a:strange:thing :to type:, but valid :nonetheless:
Use this code I put up below I think using this function your problem will be solved.
string s = "Hello:grinning: , how are you?:kissing_heart: Are you fine?:bouquet:";
string rmv = ""; string remove = "";
int i = 0; int k = 0;
A:
rmv = "";
for (i = k; i < s.Length; i++)
{
if (Convert.ToString(s[i]) == ":")
{
for (int j = i + 1; j < s.Length; j++)
{
if (Convert.ToString(s[j]) != ":")
{
rmv += s[j];
}
else
{
remove += rmv + ",";
i = j;
k = j + 1;
goto A;
}
}
}
}
string[] str = remove.Split(',');
for (int x = 0; x < str.Length-1; x++)
{
s = s.Replace(Convert.ToString(":" + str[x] + ":"), "");
}
Console.WriteLine(s);
Console.ReadKey();
I'd use extension method like this:
public static class Helper
{
public static string MyReplace(this string dirty, char separator)
{
string newText = "";
bool replace = false;
for (int i = 0; i < dirty.Length; i++)
{
if(dirty[i] == separator) { replace = !replace ; continue;}
if(replace ) continue;
newText += dirty[i];
}
return newText;
}
}
Usage:
richTextBox2.Text = richTextBox2.Text.MyReplace(':');
This method show be better in terms of performance compare to one with Regex
I would split the text with the ':' and then build the string excluding the found emoji names.
const char marker = ':';
var textSections = text.Split(marker);
var emojiRemovedText = string.Empty;
var notMatchedCount = 0;
textSections.ToList().ForEach(section =>
{
if (emojiNames.Contains(section))
{
notMatchedCount = 0;
}
else
{
if (notMatchedCount++ > 0)
{
emojiRemovedText += marker.ToString();
}
emojiRemovedText += section;
}
});