my input is abc#xyz.com
I want to replace xyz.com with mnop.com
So the final result will be abc#mnop.com
The present way
var input = "abc#xyz.com";
var output = input.Split('#')[0] + "#mnop.com";
What is the appropriate way?Any regular expression?
Replace function sample (with correct exception handle)
/// <summary>
/// replace email domain
/// </summary>
/// <param name="email"> email </param>
/// <param name="newDomain"> new domain </param>
/// <returns></returns>
private string ReplaceMailDomain(string email, string newDomain)
{
if (email == null) throw new ArgumentNullException("email");
int pos = email.IndexOf('#');
if (pos < 0)
{
throw new ArgumentException("Invalid email", "email");
}
else
{
return email.Substring(0, pos + 1) + newDomain;
}
}
Usage:
string email = ReplaceMailDomain("abc#xyz.com", "mnop.com");
If you know before hand the string you are looking for, you can simply use the normal Replace(string toFind, string replacement). You can use indexof and substring to get the domain name.
Given the below:
string input = "abc#xyz.com";
string domain = input.Substring(input.IndexOf('#') + 1);
Console.WriteLine(input.Replace(domain, "mnop.com"));
It yields
abc#mnop.com
If you just want to "take something before # sign and append some domain name", then one of possible approaches is
var input = "abc#xyz.com";
var output = input.Substring(0, input.IndexOf('#')) + "#mnop.com";
It is slightly "lightweight" than using Split because it doesn't creates array (and in fact you doesn't need array since you're using only its first element).
Assuming the address will be valid, meaning there is only one # character, you can use the simple Replace() function
var domain = "xyz.com";
var newdomain = "xyz.com";
var input = "abc#xyz.com";
var output = input.Replace("#" + domain, "#" + newdomain);
Regexps would be overkill for this.
If you want to remove any domain name and replace it, then use Substring() and IndexOf() for that
var output = input.Substring(0, input.IndexOf('#') + 1) + newdomain;
Note that this will throw an exception if the string doesn't contain the # character.
My code should be translating a phrase into pig latin. Every word must have an "ay" at the end and every first letter of each word should be placed before "ay"
ex wall = "allway"
any ideas? this is the easiest way i could think of..
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace english_to_pig_latin
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("THIS IS A English to Pig Latin translator");
Console.WriteLine("ENTER Phrase");
string[] phrase = Console.ReadLine().Split(' ');
int words = phrase.Length;
StringBuilder sb = new StringBuilder();
for (int i = 0; i < words; i++)
{
//to add ay in the end
/*sb.Append(phrase[i].ToString());
sb.Append("ay ");
Console.WriteLine(sb);*/
}
Console.ReadLine();
}
}
}
First you need to define your pig-latin rules. your description lacks real pig-latin rules. for instance, English "sharp" is correctly "Pig-Latinized" as 'arpshay', not 'harpsay', as your explanation above explained. (But i prefer to use 'arp-sh-ay' to facilitate reading of PigLatin as well as using hyphens make it possible to reverse translate back into English.) i suggest you first find some rules for Pig-Latin. Your start is a good start. Your code now separates a phrase into (almost) words. Note that your code will turn "Please, Joe" into "Please," and "Joe" tho, and you probably do not want that comma sent to your word-by-word translator.
when defining your rules, i suggest you consider how to Pig-Latin-ize these words:
hello --> 'ellohay' (a normal word),
string --> 'ingstray' ('str' is the whole consonant string moved to the end),
apple --> 'appleway', 'appleay', or 'appleyay', (depending on your dialect of Pig-Latin),
queen --> 'eenquay' ('qu' is the consonant string here),
yellow --> 'ellowyay' (y is consonant here),
rhythm --> 'ythmrhay' (y is vowel here),
sky --> 'yskay' (y is vowel here).
Note that for any word that starts with 'qu' (like 'queen'), this 'qu' is a special condition that needs handled too. Note that y is probably a consonant when it begins an English word, but a vowel when in the middle or at the end of a word.
The hyphenated Pig Latin versions of these words would be:
ello-h-ay, ing-str-ay, ('apple-way', 'apple-ay', or 'apple-yay'), 'een-qu-ay', 'ellow-y-ay', 'ythm-rh-ay', and 'y-sk-ay'. The hyphenation allows both easier reading as well as an ability to reverse the Pig Latin back into English by a computer parser. But unfortunately, many people just cram the Pig Latin word together without showing any hyphenation separation, so reversing the translation cannot be done simply without ambiguity.
Real pig-latin really goes by the sound of the word, not the spelling, so without a very complex word to phoneme system, this is way too difficult. but most (good) pig-latin writing translators handle the above cases and ignore other exceptions because English is really a very bad language when it comes to phonetically sounding out words.
So my first suggestion is get a set of rules. my 2nd suggestion is use two functions, PigLatinizePhrase() and PigLatinizeWord() where your PigLatinizePhrase() method parses a phrase into words (and punctuation), and calls PigLatinizeWord() for each word, excluding any punctuation. you can use a simple loop thru each character and test for char.IsLetter to determine if it's a letter or not. if it's a letter then add it to a string builder and move to the next letter. if it's not a letter and the string builder is not empty then send that word to your word parser to parse it, and then add the non-letter to your result. this would be your logic for your PigLatinizePhrase() method. Here is my code which does just that:
/// <summary>
/// </summary>
/// <param name="eng">English text, paragraphs, etc.</param>
/// <param name="suffixWithNoOnset">Used to differentiate between Pig Latin dialects.
/// Known dialects may use any of: "ay", "-ay", "way", "-way", "yay", or "-yay".
/// Cooresponding translations for 'egg' will yield: "eggay", "egg-ay", "eggway", "egg-way", "eggyay", "egg-yay".
/// Or for 'I': "Iay", "I-ay", "Iway", "I-way", "Iyay", "I-yay".
/// </param>
/// <returns></returns>
public static string PigLatinizePhrase(string eng, string suffixWithNoOnset = "-ay")
{
if (eng == null) { return null; } // don't break if null
var word = new StringBuilder(); // only current word, built char by char
var pig = new StringBuilder(); // pig latin text
char prevChar = '\0';
foreach (char thisChar in eng)
{
// the "'" test is so "I'll", "can't", and "Ashley's" will work right.
if (char.IsLetter(thisChar) || thisChar == '\'')
{
word.Append(thisChar);
}
else
{
if (word.Length > 0)
{
pig.Append(PigLatinizeWord(word.ToString(), suffixWithNoOnset));
word = new StringBuilder();
}
pig.Append(thisChar);
}
prevChar = thisChar;
}
if (word.Length > 0)
{
pig.Append(PigLatinizeWord(word.ToString(), suffixWithNoOnset));
}
return pig.ToString();
} // public static string PigLatinizePhrase(string eng, string suffixWithNoOnset = "-ay")
The suffixWithNoOnset variable is simply passed directly to the PigLatinizeWord() method and it determines exactly which 'dialect' of Pig Latin will be used. (See the XML comment before the method in the source code for more clarity.)
For the PigLatinizeWord() method, upon actually programming it, i found that it was very convenient to split this functionality into two methods, one method to parse the English word into the 2 parts that Pig Latin cares about, and another to actually do what is desired with those 2 parts, depending on which version of Pig Latin is desired. Here's the source code for these two functions:
/// <summary>
/// </summary>
/// <param name="eng">English word before being translated to Pig Latin.</param>
/// <param name="suffixWithNoOnset">Used to differentiate between Pig Latin dialects.
/// Known dialects may use any of: "ay", "-ay", "way", "-way", "yay", or "-yay".
/// Cooresponding translations for 'egg' will yield: "eggay", "egg-ay", "eggway", "egg-way", "eggyay", "egg-yay".
/// Or for 'I': "Iay", "I-ay", "Iway", "I-way", "Iyay", "I-yay".
/// </param>
/// <returns></returns>
public static string PigLatinizeWord(string eng, string suffixWithNoOnset = "-ay")
{
if (eng == null || eng.Length == 0) { return eng; } // don't break if null or empty
string[] onsetAndEnd = GetOnsetAndEndOfWord(eng);
// string h = string.Empty;
string o = onsetAndEnd[0]; // 'Onset' of first syllable that gets moved to end of word
string e = onsetAndEnd[1]; // 'End' of word, without the onset
bool hyphenate = suffixWithNoOnset.Contains('-');
// if (hyphenate) { h = "-"; }
var sb = new StringBuilder();
if (e.Length > 0) { sb.Append(e); if (hyphenate && o.Length > 0) { sb.Append('-'); } }
if (o.Length > 0) { sb.Append(o); if (hyphenate) { sb.Append('-'); } sb.Append("ay"); }
else { sb.Append(suffixWithNoOnset); }
return sb.ToString();
} // public static string PigLatinizeWord(string eng)
public static string[] GetOnsetAndEndOfWord(string word)
{
if (word == null) { return null; }
// string[] r = ",".Split(',');
string uppr = word.ToUpperInvariant();
if (uppr.StartsWith("QU")) { return new string[] { word.Substring(0,2), word.Substring(2) }; }
int x = 0; if (word.Length <= x) { return new string[] { string.Empty, string.Empty }; }
if ("AOEUI".Contains(uppr[x])) // tests first letter/character
{ return new string[] { word.Substring(0, x), word.Substring(x) }; }
while (++x < word.Length)
{
if ("AOEUIY".Contains(uppr[x])) // tests each character after first letter/character
{ return new string[] { word.Substring(0, x), word.Substring(x) }; }
}
return new string[] { string.Empty, word };
} // public static string[] GetOnsetAndEndOfWord(string word)
I have written a PigLatinize() method in JavaScript before, which was a lot of fun for me. :) I enjoyed making my C# version with more features, giving it the ability to translate to 6 varyious 'dialects' of Pig Latin, especially since C# is my favorite (programming) language. ;)
I think you need this transformation: phrase[i].Substring(1) + phrase[i][0] + "ay"
Is there any way to format a string by name rather than position in C#?
In python, I can do something like this example (shamelessly stolen from here):
>>> print '%(language)s has %(#)03d quote types.' % \
{'language': "Python", "#": 2}
Python has 002 quote types.
Is there any way to do this in C#? Say for instance:
String.Format("{some_variable}: {some_other_variable}", ...);
Being able to do this using a variable name would be nice, but a dictionary is acceptable too.
There is no built-in method for handling this.
Here's one method
string myString = "{foo} is {bar} and {yadi} is {yada}".Inject(o);
Here's another
Status.Text = "{UserName} last logged in at {LastLoginDate}".FormatWith(user);
A third improved method partially based on the two above, from Phil Haack
Update: This is now built-in as of C# 6 (released in 2015).
String Interpolation
$"{some_variable}: {some_other_variable}"
I have an implementation I just posted to my blog here: http://haacked.com/archive/2009/01/04/fun-with-named-formats-string-parsing-and-edge-cases.aspx
It addresses some issues that these other implementations have with brace escaping. The post has details. It does the DataBinder.Eval thing too, but is still very fast.
Interpolated strings were added into C# 6.0 and Visual Basic 14
Both were introduced through new Roslyn compiler in Visual Studio 2015.
C# 6.0:
return "\{someVariable} and also \{someOtherVariable}" OR
return $"{someVariable} and also {someOtherVariable}"
source: what's new in C#6.0
VB 14:
return $"{someVariable} and also {someOtherVariable}"
source: what's new in VB 14
Noteworthy features (in Visual Studio 2015 IDE):
syntax coloring is supported - variables contained in strings are highlighted
refactoring is supported - when renaming, variables contained in strings get renamed, too
actually not only variable names, but expressions are supported - e.g. not only {index} works, but also {(index + 1).ToString().Trim()}
Enjoy! (& click "Send a Smile" in the VS)
You can also use anonymous types like this:
public string Format(string input, object p)
{
foreach (PropertyDescriptor prop in TypeDescriptor.GetProperties(p))
input = input.Replace("{" + prop.Name + "}", (prop.GetValue(p) ?? "(null)").ToString());
return input;
}
Of course it would require more code if you also want to parse formatting, but you can format a string using this function like:
Format("test {first} and {another}", new { first = "something", another = "something else" })
There doesn't appear to be a way to do this out of the box. Though, it looks feasible to implement your own IFormatProvider that links to an IDictionary for values.
var Stuff = new Dictionary<string, object> {
{ "language", "Python" },
{ "#", 2 }
};
var Formatter = new DictionaryFormatProvider();
// Interpret {0:x} where {0}=IDictionary and "x" is hash key
Console.WriteLine string.Format(Formatter, "{0:language} has {0:#} quote types", Stuff);
Outputs:
Python has 2 quote types
The caveat is that you can't mix FormatProviders, so the fancy text formatting can't be used at the same time.
The framework itself does not provide a way to do this, but you can take a look at this post by Scott Hanselman. Example usage:
Person p = new Person();
string foo = p.ToString("{Money:C} {LastName}, {ScottName} {BirthDate}");
Assert.AreEqual("$3.43 Hanselman, {ScottName} 1/22/1974 12:00:00 AM", foo);
This code by James Newton-King is similar and works with sub-properties and indexes,
string foo = "Top result for {Name} was {Results[0].Name}".FormatWith(student));
James's code relies on System.Web.UI.DataBinder to parse the string and requires referencing System.Web, which some people don't like to do in non-web applications.
EDIT: Oh and they work nicely with anonymous types, if you don't have an object with properties ready for it:
string name = ...;
DateTime date = ...;
string foo = "{Name} - {Birthday}".FormatWith(new { Name = name, Birthday = date });
See https://stackoverflow.com/questions/271398?page=2#358259
With the linked-to extension you can write this:
var str = "{foo} {bar} {baz}".Format(foo=>"foo", bar=>2, baz=>new object());
and you'll get "foo 2 System.Object".
I think the closest you'll get is an indexed format:
String.Format("{0} has {1} quote types.", "C#", "1");
There's also String.Replace(), if you're willing to do it in multiple steps and take it on faith that you won't find your 'variables' anywhere else in the string:
string MyString = "{language} has {n} quote types.";
MyString = MyString.Replace("{language}", "C#").Replace("{n}", "1");
Expanding this to use a List:
List<KeyValuePair<string, string>> replacements = GetFormatDictionary();
foreach (KeyValuePair<string, string> item in replacements)
{
MyString = MyString.Replace(item.Key, item.Value);
}
You could do that with a Dictionary<string, string> too by iterating it's .Keys collections, but by using a List<KeyValuePair<string, string>> we can take advantage of the List's .ForEach() method and condense it back to a one-liner:
replacements.ForEach(delegate(KeyValuePair<string,string>) item) { MyString = MyString.Replace(item.Key, item.Value);});
A lambda would be even simpler, but I'm still on .Net 2.0. Also note that the .Replace() performance isn't stellar when used iteratively, since strings in .Net are immutable. Also, this requires the MyString variable be defined in such a way that it's accessible to the delegate, so it's not perfect yet.
My open source library, Regextra, supports named formatting (amongst other things). It currently targets .NET 4.0+ and is available on NuGet. I also have an introductory blog post about it: Regextra: helping you reduce your (problems){2}.
The named formatting bit supports:
Basic formatting
Nested properties formatting
Dictionary formatting
Escaping of delimiters
Standard/Custom/IFormatProvider string formatting
Example:
var order = new
{
Description = "Widget",
OrderDate = DateTime.Now,
Details = new
{
UnitPrice = 1500
}
};
string template = "We just shipped your order of '{Description}', placed on {OrderDate:d}. Your {{credit}} card will be billed {Details.UnitPrice:C}.";
string result = Template.Format(template, order);
// or use the extension: template.FormatTemplate(order);
Result:
We just shipped your order of 'Widget', placed on 2/28/2014. Your {credit} card will be billed $1,500.00.
Check out the project's GitHub link (above) and wiki for other examples.
private static Regex s_NamedFormatRegex = new Regex(#"\{(?!\{)(?<key>[\w]+)(:(?<fmt>(\{\{|\}\}|[^\{\}])*)?)?\}", RegexOptions.Compiled);
public static StringBuilder AppendNamedFormat(this StringBuilder builder,IFormatProvider provider, string format, IDictionary<string, object> args)
{
if (builder == null) throw new ArgumentNullException("builder");
var str = s_NamedFormatRegex.Replace(format, (mt) => {
string key = mt.Groups["key"].Value;
string fmt = mt.Groups["fmt"].Value;
object value = null;
if (args.TryGetValue(key,out value)) {
return string.Format(provider, "{0:" + fmt + "}", value);
} else {
return mt.Value;
}
});
builder.Append(str);
return builder;
}
public static StringBuilder AppendNamedFormat(this StringBuilder builder, string format, IDictionary<string, object> args)
{
if (builder == null) throw new ArgumentNullException("builder");
return builder.AppendNamedFormat(null, format, args);
}
Example:
var builder = new StringBuilder();
builder.AppendNamedFormat(
#"你好,{Name},今天是{Date:yyyy/MM/dd}, 这是你第{LoginTimes}次登录，积分{Score:{{ 0.00 }}}",
new Dictionary<string, object>() {
{ "Name", "wayjet" },
{ "LoginTimes",18 },
{ "Score", 100.4 },
{ "Date",DateTime.Now }
});
Output:
你好,wayjet,今天是2011-05-04, 这是你第18次登录，积分{ 100.40 }
Check this one:
public static string StringFormat(string format, object source)
{
var matches = Regex.Matches(format, #"\{(.+?)\}");
List<string> keys = (from Match matche in matches select matche.Groups[1].Value).ToList();
return keys.Aggregate(
format,
(current, key) =>
{
int colonIndex = key.IndexOf(':');
return current.Replace(
"{" + key + "}",
colonIndex > 0
? DataBinder.Eval(source, key.Substring(0, colonIndex), "{0:" + key.Substring(colonIndex + 1) + "}")
: DataBinder.Eval(source, key).ToString());
});
}
Sample:
string format = "{foo} is a {bar} is a {baz} is a {qux:#.#} is a really big {fizzle}";
var o = new { foo = 123, bar = true, baz = "this is a test", qux = 123.45, fizzle = DateTime.Now };
Console.WriteLine(StringFormat(format, o));
Performance is pretty ok compared to other solutions.
I doubt this will be possible. The first thing that comes to mind is how are you going to get access to local variable names?
There might be some clever way using LINQ and Lambda expressions to do this however.
Here's one I made a while back. It extends String with a Format method taking a single argument. The nice thing is that it'll use the standard string.Format if you provide a simple argument like an int, but if you use something like anonymous type it'll work too.
Example usage:
"The {Name} family has {Children} children".Format(new { Children = 4, Name = "Smith" })
Would result in "The Smith family has 4 children."
It doesn't do crazy binding stuff like arrays and indexers. But it is super simple and high performance.
public static class AdvancedFormatString
{
/// <summary>
/// An advanced version of string.Format. If you pass a primitive object (string, int, etc), it acts like the regular string.Format. If you pass an anonmymous type, you can name the paramters by property name.
/// </summary>
/// <param name="formatString"></param>
/// <param name="arg"></param>
/// <returns></returns>
/// <example>
/// "The {Name} family has {Children} children".Format(new { Children = 4, Name = "Smith" })
///
/// results in
/// "This Smith family has 4 children
/// </example>
public static string Format(this string formatString, object arg, IFormatProvider format = null)
{
if (arg == null)
return formatString;
var type = arg.GetType();
if (Type.GetTypeCode(type) != TypeCode.Object || type.IsPrimitive)
return string.Format(format, formatString, arg);
var properties = TypeDescriptor.GetProperties(arg);
return formatString.Format((property) =>
{
var value = properties[property].GetValue(arg);
return Convert.ToString(value, format);
});
}
public static string Format(this string formatString, Func<string, string> formatFragmentHandler)
{
if (string.IsNullOrEmpty(formatString))
return formatString;
Fragment[] fragments = GetParsedFragments(formatString);
if (fragments == null || fragments.Length == 0)
return formatString;
return string.Join(string.Empty, fragments.Select(fragment =>
{
if (fragment.Type == FragmentType.Literal)
return fragment.Value;
else
return formatFragmentHandler(fragment.Value);
}).ToArray());
}
private static Fragment[] GetParsedFragments(string formatString)
{
Fragment[] fragments;
if ( parsedStrings.TryGetValue(formatString, out fragments) )
{
return fragments;
}
lock (parsedStringsLock)
{
if ( !parsedStrings.TryGetValue(formatString, out fragments) )
{
fragments = Parse(formatString);
parsedStrings.Add(formatString, fragments);
}
}
return fragments;
}
private static Object parsedStringsLock = new Object();
private static Dictionary<string,Fragment[]> parsedStrings = new Dictionary<string,Fragment[]>(StringComparer.Ordinal);
const char OpeningDelimiter = '{';
const char ClosingDelimiter = '}';
/// <summary>
/// Parses the given format string into a list of fragments.
/// </summary>
/// <param name="format"></param>
/// <returns></returns>
static Fragment[] Parse(string format)
{
int lastCharIndex = format.Length - 1;
int currFragEndIndex;
Fragment currFrag = ParseFragment(format, 0, out currFragEndIndex);
if (currFragEndIndex == lastCharIndex)
{
return new Fragment[] { currFrag };
}
List<Fragment> fragments = new List<Fragment>();
while (true)
{
fragments.Add(currFrag);
if (currFragEndIndex == lastCharIndex)
{
break;
}
currFrag = ParseFragment(format, currFragEndIndex + 1, out currFragEndIndex);
}
return fragments.ToArray();
}
/// <summary>
/// Finds the next delimiter from the starting index.
/// </summary>
static Fragment ParseFragment(string format, int startIndex, out int fragmentEndIndex)
{
bool foundEscapedDelimiter = false;
FragmentType type = FragmentType.Literal;
int numChars = format.Length;
for (int i = startIndex; i < numChars; i++)
{
char currChar = format[i];
bool isOpenBrace = currChar == OpeningDelimiter;
bool isCloseBrace = isOpenBrace ? false : currChar == ClosingDelimiter;
if (!isOpenBrace && !isCloseBrace)
{
continue;
}
else if (i < (numChars - 1) && format[i + 1] == currChar)
{//{{ or }}
i++;
foundEscapedDelimiter = true;
}
else if (isOpenBrace)
{
if (i == startIndex)
{
type = FragmentType.FormatItem;
}
else
{
if (type == FragmentType.FormatItem)
throw new FormatException("Two consequtive unescaped { format item openers were found. Either close the first or escape any literals with another {.");
//curr character is the opening of a new format item. so we close this literal out
string literal = format.Substring(startIndex, i - startIndex);
if (foundEscapedDelimiter)
literal = ReplaceEscapes(literal);
fragmentEndIndex = i - 1;
return new Fragment(FragmentType.Literal, literal);
}
}
else
{//close bracket
if (i == startIndex || type == FragmentType.Literal)
throw new FormatException("A } closing brace existed without an opening { brace.");
string formatItem = format.Substring(startIndex + 1, i - startIndex - 1);
if (foundEscapedDelimiter)
formatItem = ReplaceEscapes(formatItem);//a format item with a { or } in its name is crazy but it could be done
fragmentEndIndex = i;
return new Fragment(FragmentType.FormatItem, formatItem);
}
}
if (type == FragmentType.FormatItem)
throw new FormatException("A format item was opened with { but was never closed.");
fragmentEndIndex = numChars - 1;
string literalValue = format.Substring(startIndex);
if (foundEscapedDelimiter)
literalValue = ReplaceEscapes(literalValue);
return new Fragment(FragmentType.Literal, literalValue);
}
/// <summary>
/// Replaces escaped brackets, turning '{{' and '}}' into '{' and '}', respectively.
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
static string ReplaceEscapes(string value)
{
return value.Replace("{{", "{").Replace("}}", "}");
}
private enum FragmentType
{
Literal,
FormatItem
}
private class Fragment
{
public Fragment(FragmentType type, string value)
{
Type = type;
Value = value;
}
public FragmentType Type
{
get;
private set;
}
/// <summary>
/// The literal value, or the name of the fragment, depending on fragment type.
/// </summary>
public string Value
{
get;
private set;
}
}
}
here is a simple method for any object:
using System.Text.RegularExpressions;
using System.ComponentModel;
public static string StringWithFormat(string format, object args)
{
Regex r = new Regex(#"\{([A-Za-z0-9_]+)\}");
MatchCollection m = r.Matches(format);
var properties = TypeDescriptor.GetProperties(args);
foreach (Match item in m)
{
try
{
string propertyName = item.Groups[1].Value;
format = format.Replace(item.Value, properties[propertyName].GetValue(args).ToString());
}
catch
{
throw new FormatException("The format string is not valid");
}
}
return format;
}
And here how to use it:
DateTime date = DateTime.Now;
string dateString = StringWithFormat("{Month}/{Day}/{Year}", date);
output : 2/27/2012
I implemented this is a simple class that duplicates the functionality of String.Format (except for when using classes). You can either use a dictionary or a type to define fields.
https://github.com/SergueiFedorov/NamedFormatString
C# 6.0 is adding this functionality right into the language spec, so NamedFormatString is for backwards compatibility.
I solved this in a slightly different way to the existing solutions.
It does the core of the named item replacement (not the reflection bit that some have done). It is extremely fast and simple...
This is my solution:
/// <summary>
/// Formats a string with named format items given a template dictionary of the items values to use.
/// </summary>
public class StringTemplateFormatter
{
private readonly IFormatProvider _formatProvider;
/// <summary>
/// Constructs the formatter with the specified <see cref="IFormatProvider"/>.
/// This is defaulted to <see cref="CultureInfo.CurrentCulture">CultureInfo.CurrentCulture</see> if none is provided.
/// </summary>
/// <param name="formatProvider"></param>
public StringTemplateFormatter(IFormatProvider formatProvider = null)
{
_formatProvider = formatProvider ?? CultureInfo.CurrentCulture;
}
/// <summary>
/// Formats a string with named format items given a template dictionary of the items values to use.
/// </summary>
/// <param name="text">The text template</param>
/// <param name="templateValues">The named values to use as replacements in the formatted string.</param>
/// <returns>The resultant text string with the template values replaced.</returns>
public string FormatTemplate(string text, Dictionary<string, object> templateValues)
{
var formattableString = text;
var values = new List<object>();
foreach (KeyValuePair<string, object> value in templateValues)
{
var index = values.Count;
formattableString = ReplaceFormattableItem(formattableString, value.Key, index);
values.Add(value.Value);
}
return String.Format(_formatProvider, formattableString, values.ToArray());
}
/// <summary>
/// Convert named string template item to numbered string template item that can be accepted by <see cref="string.Format(string,object[])">String.Format</see>
/// </summary>
/// <param name="formattableString">The string containing the named format item</param>
/// <param name="itemName">The name of the format item</param>
/// <param name="index">The index to use for the item value</param>
/// <returns>The formattable string with the named item substituted with the numbered format item.</returns>
private static string ReplaceFormattableItem(string formattableString, string itemName, int index)
{
return formattableString
.Replace("{" + itemName + "}", "{" + index + "}")
.Replace("{" + itemName + ",", "{" + index + ",")
.Replace("{" + itemName + ":", "{" + index + ":");
}
}
It is used in the following way:
[Test]
public void FormatTemplate_GivenANamedGuid_FormattedWithB_ShouldFormatCorrectly()
{
// Arrange
var template = "My guid {MyGuid:B} is awesome!";
var templateValues = new Dictionary<string, object> { { "MyGuid", new Guid("{A4D2A7F1-421C-4A1D-9CB2-9C2E70B05E19}") } };
var sut = new StringTemplateFormatter();
// Act
var result = sut.FormatTemplate(template, templateValues);
//Assert
Assert.That(result, Is.EqualTo("My guid {a4d2a7f1-421c-4a1d-9cb2-9c2e70b05e19} is awesome!"));
}
Hope someone finds this useful!
Even though the accepted answer gives some good examples, the .Inject as well as some of the Haack examples do not handle escaping. Many also rely heavily on Regex (slower), or DataBinder.Eval which is not available on .NET Core, and in some other environments.
With that in mind, I've written a simple state machine based parser that streams through characters, writing to a StringBuilder output, character by character. It is implemented as String extension method(s) and can take both a Dictionary<string, object> or object with parameters as input (using reflection).
It handles unlimited levels of {{{escaping}}} and throws FormatException when input contains unbalanced braces and/or other errors.
public static class StringExtension {
/// <summary>
/// Extension method that replaces keys in a string with the values of matching object properties.
/// </summary>
/// <param name="formatString">The format string, containing keys like {foo} and {foo:SomeFormat}.</param>
/// <param name="injectionObject">The object whose properties should be injected in the string</param>
/// <returns>A version of the formatString string with keys replaced by (formatted) key values.</returns>
public static string FormatWith(this string formatString, object injectionObject) {
return formatString.FormatWith(GetPropertiesDictionary(injectionObject));
}
/// <summary>
/// Extension method that replaces keys in a string with the values of matching dictionary entries.
/// </summary>
/// <param name="formatString">The format string, containing keys like {foo} and {foo:SomeFormat}.</param>
/// <param name="dictionary">An <see cref="IDictionary"/> with keys and values to inject into the string</param>
/// <returns>A version of the formatString string with dictionary keys replaced by (formatted) key values.</returns>
public static string FormatWith(this string formatString, IDictionary<string, object> dictionary) {
char openBraceChar = '{';
char closeBraceChar = '}';
return FormatWith(formatString, dictionary, openBraceChar, closeBraceChar);
}
/// <summary>
/// Extension method that replaces keys in a string with the values of matching dictionary entries.
/// </summary>
/// <param name="formatString">The format string, containing keys like {foo} and {foo:SomeFormat}.</param>
/// <param name="dictionary">An <see cref="IDictionary"/> with keys and values to inject into the string</param>
/// <returns>A version of the formatString string with dictionary keys replaced by (formatted) key values.</returns>
public static string FormatWith(this string formatString, IDictionary<string, object> dictionary, char openBraceChar, char closeBraceChar) {
string result = formatString;
if (dictionary == null || formatString == null)
return result;
// start the state machine!
// ballpark output string as two times the length of the input string for performance (avoids reallocating the buffer as often).
StringBuilder outputString = new StringBuilder(formatString.Length * 2);
StringBuilder currentKey = new StringBuilder();
bool insideBraces = false;
int index = 0;
while (index < formatString.Length) {
if (!insideBraces) {
// currently not inside a pair of braces in the format string
if (formatString[index] == openBraceChar) {
// check if the brace is escaped
if (index < formatString.Length - 1 && formatString[index + 1] == openBraceChar) {
// add a brace to the output string
outputString.Append(openBraceChar);
// skip over braces
index += 2;
continue;
}
else {
// not an escaped brace, set state to inside brace
insideBraces = true;
index++;
continue;
}
}
else if (formatString[index] == closeBraceChar) {
// handle case where closing brace is encountered outside braces
if (index < formatString.Length - 1 && formatString[index + 1] == closeBraceChar) {
// this is an escaped closing brace, this is okay
// add a closing brace to the output string
outputString.Append(closeBraceChar);
// skip over braces
index += 2;
continue;
}
else {
// this is an unescaped closing brace outside of braces.
// throw a format exception
throw new FormatException($"Unmatched closing brace at position {index}");
}
}
else {
// the character has no special meaning, add it to the output string
outputString.Append(formatString[index]);
// move onto next character
index++;
continue;
}
}
else {
// currently inside a pair of braces in the format string
// found an opening brace
if (formatString[index] == openBraceChar) {
// check if the brace is escaped
if (index < formatString.Length - 1 && formatString[index + 1] == openBraceChar) {
// there are escaped braces within the key
// this is illegal, throw a format exception
throw new FormatException($"Illegal escaped opening braces within a parameter - index: {index}");
}
else {
// not an escaped brace, we have an unexpected opening brace within a pair of braces
throw new FormatException($"Unexpected opening brace inside a parameter - index: {index}");
}
}
else if (formatString[index] == closeBraceChar) {
// handle case where closing brace is encountered inside braces
// don't attempt to check for escaped braces here - always assume the first brace closes the braces
// since we cannot have escaped braces within parameters.
// set the state to be outside of any braces
insideBraces = false;
// jump over brace
index++;
// at this stage, a key is stored in current key that represents the text between the two braces
// do a lookup on this key
string key = currentKey.ToString();
// clear the stringbuilder for the key
currentKey.Clear();
object outObject;
if (!dictionary.TryGetValue(key, out outObject)) {
// the key was not found as a possible replacement, throw exception
throw new FormatException($"The parameter \"{key}\" was not present in the lookup dictionary");
}
// we now have the replacement value, add the value to the output string
outputString.Append(outObject);
// jump to next state
continue;
} // if }
else {
// character has no special meaning, add it to the current key
currentKey.Append(formatString[index]);
// move onto next character
index++;
continue;
} // else
} // if inside brace
} // while
// after the loop, if all braces were balanced, we should be outside all braces
// if we're not, the input string was misformatted.
if (insideBraces) {
throw new FormatException("The format string ended before the parameter was closed.");
}
return outputString.ToString();
}
/// <summary>
/// Creates a Dictionary from an objects properties, with the Key being the property's
/// name and the Value being the properties value (of type object)
/// </summary>
/// <param name="properties">An object who's properties will be used</param>
/// <returns>A <see cref="Dictionary"/> of property values </returns>
private static Dictionary<string, object> GetPropertiesDictionary(object properties) {
Dictionary<string, object> values = null;
if (properties != null) {
values = new Dictionary<string, object>();
PropertyDescriptorCollection props = TypeDescriptor.GetProperties(properties);
foreach (PropertyDescriptor prop in props) {
values.Add(prop.Name, prop.GetValue(properties));
}
}
return values;
}
}
Ultimately, all the logic boils down into 10 main states - For when the state machine is outside a bracket and likewise inside a bracket, the next character is either an open brace, an escaped open brace, a closed brace, an escaped closed brace, or an ordinary character. Each of these conditions is handled individually as the loop progresses, adding characters to either an output StringBuffer or a key StringBuffer. When a parameter is closed, the value of the key StringBuffer is used to look up the parameter's value in the dictionary, which then gets pushed into the output StringBuffer. At the end, the value of the output StringBuffer is returned.
string language = "Python";
int numquotes = 2;
string output = language + " has "+ numquotes + " language types.";
Edit:
What I should have said was, "No, I don't believe what you want to do is supported by C#. This is as close as you are going to get."
I have a string that can look like this: 12345, this 123456 or this: 1234567.
I'd like to make each string look like this: 123-45, this: 1234-56 or this: 12345-67.
How can I do this in C#?
string myString = "1234567";
if(myString.Length > 1)
string dashed = myString.Insert(myString.Length - 2, "-");
EDIT: Added check based on comment, but depends on how such strings should be handled. (e.g. dashed even if length = 2?)
Take a look at String.Format(), My guess is you want something like String.Format("{0:##-##}",< value >);
http://msdn.microsoft.com/en-us/library/0c899ak8.aspx
Examples shown with powershell, which uses the same corelibs
PS C:\Users\Phyx> [string]::Format("{0:##-##}",1234)
12-34
PS C:\Users\Phyx> [string]::Format("{0:##-##}",123445)
1234-45
PS C:\Users\Phyx> [string]::Format("{0:##-##}",12)
-12
PS C:\Users\Phyx> [string]::Format("{0:0#-##}",12)
00-12
PS C:\Users\Phyx> [string]::Format("{0:##-##}",122)
1-22
I'm assuming you want to add a dash two characters before the end of the string.
string number = "12345";
if(number.Length > 2)
string result = number.Insert(number.Length-2, "-");
else
//error checking
string s = "teststring";
string newString = s.Insert(s.Length-2,"-");
This is assuming you want the '-' to appear two from the end :-)
This could be handy (untested)
/// <summary>
/// Takes a string and and inserts a spacer character at
/// a specifed distance from the end
/// </summary>
/// <param name="input">string to modify</param>
/// <param name="spacer">string to insert</param>
/// <param name="positionFromEnd">insertion point</param>
/// <returns></returns>
protected string AddSpacer(string input, string spacer, int positionFromEnd)
{
string outputString = string.Empty;
if (input.Length >= positionFromEnd)
{
outputString = input.Insert(input.Length - positionFromEnd, spacer);
}
else
{
throw new Exception("The position you tried to insert the spacer into doesn't exist");
}
return outputString;
}