String Extension Methods in C# .NET can make life so much easier. Everyday functions that used to require extended syntax with a return value are a thing of the past. Now with Microsoft Visual Studio, we can just add a using to our Extensions collection and have full use of them from our Share Library.What is a String Extension Method?
An extension method is simply an additional method. It is a way of attaching additional functionality to a type which is available to you throughout your code without need to instantiate another class.
There’s plenty of best practices for extension methods. A great article is here on Microsoft’s site.
ToBoolean() Extension Method
Probably my most used and handiest is a simple one. There are so many times when we receive text, whether in a JSON payload or in a view that we need to see if it is a legitimate boolean value.
Here is a simple implementation of ToBoolean()
/// <summary>
/// Convert a string to a boolean
/// Yasgar Technology Group, Inc.
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
public static bool ToBoolean(this string value)
{
if (value == null) { return false; }
if (value.Trim().ToLower() == "true" || value == "1" || value == "yes")
{ return true; }
else
{ return false; }
}
This is a simple implementation that does a quick compare against a set of strings.
IsNumericInteger() Extension Method
Often, during a view post back, I need to determine if a particular value is numeric that was accepted in a text box. While I usually try to validate this type of input using javascript, there are many ways that people can bypass that validation. I use this specific one to validate that this value is indeed an integer and not a decimal.
/// <summary>
/// Return bool whether the value in the string is a numeric integer
/// Yasgar Technology Group, Inc. - www.ytgi.com
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
public static bool IsNumericInteger(this string value)
{
return long.TryParse(value, out long _tempvalue);
}
Here is a simple sample implementation that does a quick TryParse() to see if it is a pass or fail.
IsNumericDecimal() Extension Method
Often there are numeric fields that you’re receiving via a post back or JSON or XML payload. This is a quick way to determine if it’s a decimal fit or not. Remember, that integers will pass this test as well. So use the IsNumericInteger() extension method if you want to determine if the numeric value has a decimal in it.
/// <summary>
/// Return bool whether the value in the string is a numeric decimal
/// Yasgar Technology Group, Inc. - www.ytgi.com
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
public static bool IsNumericDecimal(this string value)
{
return decimal.TryParse(value, out decimal _tempvalue);
}
ToDateFromCCYYMMDD() Extension Method
There are often cases where dates are passed around in CCYYMMDD format, such as 20220329. This is a preferred method for me when I need to transfer a date as a query string parameter argument and don’t want the mess of a full DateTime. This extension method converts that string to a DateTime object.
/// <summary>
/// Convert a string in CCYYMMDD format to a valid date
/// Yasgar Technology Group, Inc. - www.ytgi.com
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
public static DateTime ToDateFromCCYYMMDD(this string value)
{
if (!string.IsNullOrWhiteSpace(value))
{
if (value == "99999999")
{
return DateTime.MaxValue;
}
else
{
string _value = value.Trim();
if (_value.IsNumericInteger() && _value.Trim().Length == 8)
{
int.TryParse(_value.Substring(0, 4), out int year);
int.TryParse(_value.Substring(4, 2), out int month);
int.TryParse(_value.Substring(6, 2), out int day);
DateTime datItem = new DateTime(year, month, day);
return datItem;
}
}
}
return DateTime.MinValue;
}
Notice that I check for the “99999999” string. This is a very popular marker for “no expiration” date, especially in mainframe data.
ToDateFromString() Extension Method
This is a variation on the ToDateFromCCYYMMDD() extension method. You might ask why I would have an extension method that probably does the same thing as DateTime.TryParse()? Well, simple, I’ve worked with lots of data where they have dates like “99999999” and “99/99/9999” which I want to handle properly.
/// <summary>
/// Convert a string in MM/DD/CCYY format to a valid date
/// Yasgar Technology Group, Inc. - www.ytgi.com
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
public static DateTime ToDateFromString(this string value)
{
if (!string.IsNullOrWhiteSpace(value))
{
if ((value == "99999999") || (value == "99/99/9999"))
{
return DateTime.MaxValue;
}
else
{
if (!string.IsNullOrWhiteSpace(value))
{
DateTime.TryParse(value, out DateTime _value);
return _value;
}
else
{
return DateTime.MinValue;
}
}
}
return DateTime.MinValue;
}
Notice it does use the standard DateTime.TryParse(), but only after it checks for funky dates. You may also want to put in checks for dates that are popular in your environment, such as the old SQL Server minimum date of “1/1/1753”
Trim(int MaxLength) (Accepting a maximum length)
This extension method accepts an integer specifying the maximum length of the returned string. I use this method all the time, especially when stuffing data into old data tables where data needs to be truncated. To be honest, I find it hard to believe that after all this time, it’s still not an overload in the framework.
/// <summary>
/// Trim a string down to a particular size
/// Yasgar Technology Group, Inc. - www.ytgi.com
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
public static string Trim(this string value, int p_MaxLength)
{
try
{
if (value != null)
{
return value.Substring(0, Math.Min(p_MaxLength, value.Length));
}
else
{
return string.Empty;
}
}
catch (Exception)
{
throw;
}
}
Remember, you should never just randomly trim data without assessing whether it is going to cause data corruption. Important data should not be truncated with a method like this unless you’re logging the activity somewhere.
RemoveSpecialChars(bool p_DashOkay = false, bool p_HashOkay = false)
This is one of my favorite extension methods, not only because I use it so often when validating data, but because it’s proven to be so versatile that I haven’t had to modify very much over the years. This method accepts two parameters to allow you to keep dashes and hash signs in the return if you want. They both default to false if you don’t set them.
/// <summary>
/// Remove special characters from a string with option to
/// retain Dashes and Hash signs
/// Yasgar Technology Group, Inc. - www.ytgi.com
/// </summary>
/// <param name="value"></param>
/// <param name="dashOkay"></param>
/// <param name="hashOkay"></param>
/// <returns></returns>
public static string RemoveSpecialChars(this string value,
bool dashOkay = false,
bool hashOkay = false)
{
try
{
StringBuilder sb = new StringBuilder();
if (value != null)
{
if (dashOkay && hashOkay)
{
foreach (char c in value)
{
if ((c >= '0' && c <= '9') ||
(c >= 'A' && c <= 'Z') ||
(c >= 'a' && c <= 'z') ||
c == '-' ||
c == '#' ||
c == ' ')
{
sb.Append(c);
}
}
}
else if (dashOkay && hashOkay == false)
{
foreach (char c in value)
{
if ((c >= '0' && c <= '9') ||
(c >= 'A' && c <= 'Z') ||
(c >= 'a' && c <= 'z') ||
c == '-' || c == ' ')
{
sb.Append(c);
}
}
}
else if (dashOkay == false && hashOkay)
{
foreach (char c in value)
{
if ((c >= '0' && c <= '9') ||
(c >= 'A' && c <= 'Z') ||
(c >= 'a' && c <= 'z') ||
c == '#' || c == ' ')
{
sb.Append(c);
}
}
}
else if (!dashOkay && !hashOkay)
{
foreach (char c in value)
{
if ((c >= '0' && c <= '9') ||
(c >= 'A' && c <= 'Z') ||
(c >= 'a' && c <= 'z') ||
c == ' ')
{
sb.Append(c);
}
}
}
}
return sb.ToString();
}
catch (Exception)
{
throw;
}
}
RemoveSpaces(bool StripInternal = false)
The standard Trim() extension method in the .NET framework will remove spaces from the beginning and end, but does it remove spaces inside the string? No, of course not. But there are times when that is needed and I have just the method read for it. It also trims the front and back as well, so no need to do an extra Trim() on it.
/// <summary>
/// Strip spaces from a string
/// Yasgar Technology Group, Inc. - www.ytgi.com
/// </summary>
/// <param name="value"></param>
/// <param name="StripInternal">strip spaces from within the string</param>
/// <returns></returns>
public static string RemoveSpaces(this string value, bool StripInternal = false)
{
if (!string.IsNullOrWhiteSpace(value))
if (StripInternal)
{
return new string(value.ToCharArray()
.Where(c => !Char.IsWhiteSpace(c))
.ToArray());
}
else
{
return value.Trim();
}
else
{
return string.Empty;
}
}
ToDecimal() Extension Method
If you need to retrieve a decimal value from a string, you can use this extension method. It will actually return a nullable decimal (decimal?). It will be null if the value could not be coerced into a decimal. This one could be used in place of the IsNumericDecimal() method if you need to retrieve the value and not simply pass it on if it validates. There is the extra step to check whether the return value is null though.
/// <summary>
/// Convert a string to a Decimal, return null if fails
/// Yasgar Technology Group, Inc. - www.ytgi.com
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
public static decimal? ToDecimal(this string value)
{
if (decimal.TryParse(value, out decimal decItem))
{ return decItem; }
else
{ return null; }
}
These are two powerful extension methods that I group together. They come in so handy for encrypting and decrypting values on the fly. While it’s probably not the greatest plan to use this for an encryption strategy, I often use them while data is in flight. For instance, I parse a text file and save it to a staging database table for later processing. If there is Protected Health Information (PHI), or even Personally Identifiable Information (PII), then I’ll use this method to protect it from prying eyes before it winds up in its final resting place.
Both of these extension methods make use of the CRijndael namespaces in the framework.
ToProperCase()
How often do we need to convert a standard text string to proper or title case. All the time! So this is a solution for your needs!
using System.Globalization;
using System.Threading;
/// <summary>
/// Convert a string to Proper case
/// based on the current thread culture
/// Yasgar Technology Group, Inc. - www.ytgi.com
/// </summary>
/// <param name="text"></param>
/// <returns></returns>
public static string ToProperCase(this string text)
{
if (text != null)
{
CultureInfo _cultureInfo = Thread.CurrentThread.CurrentCulture;
TextInfo textInfo = _cultureInfo.TextInfo;
// Send in the text as lower case to allow the method to
// make all the decisions
return textInfo.ToTitleCase(text.ToLower());
}
else
{
return text;
}
}
If you love Extension Methods, take a look at some other posts I have about others:
OrderBy Extension for Linq Queries
Knock out 1/1/0001 Dates in MVC
Extension Method to Convert Types
Stay tuned for more extension methods that I’ve used for years coming soon!