Develop Reference

Contains doen't check in the date range

I have a date range come like this,
string ActualReleaseDates ="7/8/2016, 7/9/2016, 7/11/2016,7/3/2016,7/10/2016,7/17/2016,7/24/2016,7/31/2016";
string NewsReleasedDate ="07/11/2016";
I want to check NewsReleaseDate is inside the ActualReleaseDates
But in the following code it return as a false.
if (ActualReleaseDates.Split(',').Contains(NewsReleasedDate.TrimStart(new Char[] { '0' })))
{
//some code here
}

The immediate problem is that after splitting your ActualReleaseDates string, there isn't an entry of "7/11/2016"... instead, there's an entry of " 7/11/2016"... note the space.
But more fundamentally, just trimming the start of NewsReleasedDate won't help if the value is something like "07/08/2016"... what you should be doing is handling these values as dates, rather than as strings:
Split ActualReleaseDates by comma, then parse each value (after trimming whitespace) in an appropriate format (which I suspect is M/d/yyyy) so that you get a List<DateTime>.
Parse NewsReleasedDate in the appropriate format, which I suspect is MM/dd/yyyy, so you get a DateTime.
See whether the parsed value from the second step occurs in the list from the first step.
(I'd personally recommend using Noda Time and parsing to LocalDate values, but I'm biased...)
Fundamentally, you're trying to see whether one date occurs in a list of dates... so make sure you get your data into its most appropriate representation as early as possible. Ideally, avoid using strings for this at all... we don't know where your data has come from, but if it started off in another representation and was converted into text, see if you can avoid that conversion.

The white space problem. You can use trim() and ' 7/11/2016' will be '7/11/2016'
var ActualReleaseDates = "7/8/2016, 7/9/2016, 7/11/2016,7/3/2016,7/10/2016,7/17/2016,7/24/2016,7/31/2016";
var NewsReleasedDate = "07/11/2016";
var splitActualReleaseDates = ActualReleaseDates.Split(',').Select(x => x.Trim());
if (splitActualReleaseDates.Contains(NewsReleasedDate.TrimStart(new Char[] { '0' })))
{
}

You can use linq to convert your strings into DateTime objects and compare them instead of strings
string ActualReleaseDates ="7/8/2016,7/9/2016,7/11/2016,7/3/2016,7/10/2016,7/17/2016,7/24/2016,7/31/2016";
string NewsReleasedDate ="07/11/2016";
var releaseDates = ActualReleaseDates.Split(',').Select(x => DateTime.Parse(x));
var newsReleased = DateTime.Parse(NewsReleaseDate);
if (releaseDates.Contains(newsReleased))
{
//some code here
}
please note that DateTime is parsed respectively to the current Culture. You can use DateTime.ParseExact if you want to specify exact date format.

You can Prase to DateTime before doing the query like this:
(I think this is the most accurate and guaranteed way to compare dates)
Func<string, DateTime> stringToDate = s => DateTime.ParseExact(s.Trim(), "M/d/yyyy",
CultureInfo.InvariantCulture);
DateTime newReleaseDateTime = stringToDate(NewsReleasedDate);
bool result = ActualReleaseDates.Split(',').Select(x => stringToDate(x))
.Contains(newReleaseDateTime);

It returns false because of the date 07/11/2016 stored in NewsReleasedDate is stored as string with a '0' at the begining. And in the ActualReleaseDates string you have white spaces between the ',' and numbers.
Try to rewrite theese strings like this :
ActualReleaseDates ="7/8/2016,7/9/2016,7/11/2016,7/3/2016,7/10/2016,7/17/2016,7/24/2016,7/31/2016"; // white spaces removed.
and the variable like this :
NewsReleasedDate ="7/11/2016"; // 0 removed
This is my code example :
string ActualReleaseDates = "7/8/2016,7/9/2016,7/11/2016,7/3/2016,7/10/2016,7/17/2016,7/24/2016,7/31/2016";
string NewsReleasedDate = "7/11/2016";
string[] dates = ActualReleaseDates.Split(',');
Console.WriteLine(dates.Contains(NewsReleasedDate));
This is not the best way to compare dates, you can use Date class which is usefull to do this kind of comparations.

Extracting a substring of variable length from a string

I need to extract a variable length decimal number from a string using c# and .NET. The input string is like $PTNTHPR,352.5,N,2.3,N,4.6,N,16*. I need the first occurrence of decimal number, i.e the 352.5 part. The numerical value ranges from 0.0 to 360.0 and I need that number from that string.
I searched a lot and got solution for a fixed length sub string but here I have variable length to extract. I have not tried with any code yet.

If it is always in this format you can use String.Split and decimal.Parse
var data = #"$PTNTHPR,352.5,N,2.3,N,4.6,N,16*";
var d = decimal.Parse(data.Split(new[]{','})[1]);
Console.WriteLine(d);
This is just a sample code to guide you. You should add additional exception handling logic to this, Also consider using decimal.TryParse
If you want to find the first occurance of decimal value you split the string and parse them one by one.
var data = #"$PTNTHPR,352.5,N,2.3,N,4.6,N,16*";
var splited = data.Split(new[]{','});
decimal? value = null;
foreach (var part in splited)
{
decimal parsed;
if (decimal.TryParse(part, out parsed))
{
value = parsed;
break;
}
}
Console.WriteLine(value);

First occurence in any of the tokens? Use String.Split to separate them and LINQ to find the first. You can use decimal.TryParse to check if it's parsable:
decimal? firstParsableToken = "$PTNTHPR,352.5,N,2.3,N,4.6,N,16*".Split(',')
.Select(s => s.TryGetDecimal(NumberFormatInfo.InvariantInfo))
.FirstOrDefault(d => d.HasValue);
Used this simple extension method to parse it to decimal?:
public static decimal? TryGetDecimal(this string item, IFormatProvider formatProvider = null, NumberStyles nStyles = NumberStyles.Any)
{
if (formatProvider == null) formatProvider = NumberFormatInfo.CurrentInfo;
decimal d = 0m;
bool success = decimal.TryParse(item, nStyles, formatProvider, out d);
if (success)
return d;
else
return null;
}

If the string is always comma separated, can you not use string.Split() to get each section, then use double.TryParse() to test if that part is numeric?

public static class Helper
{
public static string MyExtract(this string s)
{
return s.Split(',').First(str => Regex.IsMatch(str, #"[0-9.,]"));
}
}
Use it like this: string str = "$PTNTHPR,352.5,N,2.3,N,4.6,N,16*".MyExtract();
Then convert it to double/decimal if you need it.

Insert spaces into string using string.format

I've been using C# String.Format for formatting numbers before like this (in this example I simply want to insert a space):
String.Format("{0:### ###}", 123456);
output:
"123 456"
In this particular case, the number is a string. My first thought was to simply parse it to a number, but it makes no sense in the context, and there must be a prettier way.
Following does not work, as ## looks for numbers
String.Format("{0:### ###}", "123456");
output:
"123456"
What is the string equivalent to # when formatting? The awesomeness of String.Format is still fairly new to me.

You have to parse the string to a number first.
int number = int.Parse("123456");
String.Format("{0:### ###}", number);
of course you could also use string methods but that's not as reliable and less safe:
string strNumber = "123456";
String.Format("{0} {1}", strNumber.Remove(3), strNumber.Substring(3));

As Heinzi pointed out, you can not have format specifier for string arguments.
So, instead of String.Format, you may use following:
string myNum="123456";
myNum=myNum.Insert(3," ");

Not very beautiful, and the extra work might outweigh the gains, but if the input is a string on that format, you could do:
var str = "123456";
var result = String.Format("{0} {1}", str.Substring(0,3), str.Substring(3));

string is not a IFormattable
Console.WriteLine("123456" is IFormattable); // False
Console.WriteLine(21321 is IFormattable); // True
No point to supply a format if the argument is not IFormattable only way is to convert your string to int or long

We're doing string manipulation, so we could always use a regex.
Adapted slightly from here:
class MyClass
{
static void Main(string[] args)
{
string sInput, sRegex;
// The string to search.
sInput = "123456789";
// The regular expression.
sRegex = "[0-9][0-9][0-9]";
Regex r = new Regex(sRegex);
MyClass c = new MyClass();
// Assign the replace method to the MatchEvaluator delegate.
MatchEvaluator myEvaluator = new MatchEvaluator(c.ReplaceNums);
// Replace matched characters using the delegate method.
sInput = r.Replace(sInput, myEvaluator);
// Write out the modified string.
Console.WriteLine(sInput);
}
public string ReplaceNums(Match m)
// Replace each Regex match with match + " "
{
return m.ToString()+" ";
}
}
How's that?
It's been ages since I used C# and I can't test, but this may work as a one-liner which may be "neater" if you only need it once:
sInput = Regex("[0-9][0-9][0-9]").Replace(sInput,MatchEvaluator(Match m => m.ToString()+" "));

There is no way to do what you want unless you parse the string first.
Based on your comments, you only really need a simple formatting so you are better off just implementing a small helper method and thats it. (IMHO it's not really a good idea to parse the string if it isn't logically a number; you can't really be sure that in the future the input string might not be a number at all.
I'd go for something similar to:
public static string Group(this string s, int groupSize = 3, char groupSeparator = ' ')
{
var formattedIdentifierBuilder = new StringBuilder();
for (int i = 0; i < s.Length; i++)
{
if (i != 0 && (s.Length - i) % groupSize == 0)
{
formattedIdentifierBuilder.Append(groupSeparator);
}
formattedIdentifierBuilder.Append(s[i]);
}
return formattedIdentifierBuilder.ToString();
}
EDIT: Generalized to generic grouping size and group separator.

The problem is that # is a Digit placeholder and it is specific to numeric formatting only. Hence, you can't use this on strings.
Either parse the string to a numeric, so the formatting rules apply, or use other methods to split the string in two.
string.Format("{0:### ###}", int.Parse("123456"));

Parse exact format not valid

I need to parse a string and convert it to DateTime . I have the following snippet :
using (StreamReader reader = new StreamReader(fichier))
{
while ((item = reader.ReadLine()) != null)
{
string[] table = item.Split('\t');
string _date = table[2];
pointages.Add(DateTime.ParseExact(_date,"yyyy-MM-dd-hh:mm:ss", CultureInfo.InvariantCulture,DateTimeStyles.None));
}
}
Edit2
the content of the file:
917 2014-06-24-07:43:47 Finger
the string _date =2014-06-24-07:43:47. When i execute the program i got this exception:
String was not recognized as a valid DateTime.
Edit
When i added a line before like this :
while ((item = reader.ReadLine()) != null)
{
string[] table = item.Split('\t');
string _date = table[2];
_date ="2014-06-24-07:43:47";
pointages.Add(DateTime.ParseExact(_date,"yyyy-MM-dd-hh:mm:ss", CultureInfo.InvariantCulture,DateTimeStyles.None));
}
It Works!!!
What are the reasons of this error?
How can i fix it?

Your sample string works for me, so it must be a different string. Use the debugger. Maybe it is actually using 24h clock like 17:43:47, then you need HH instead of hh.
You: no, it is really the string i've posted.
That's impossible. Maybe it has leading or trailing spaces, use Trim first:
_date = _date.Trim();
Trim removes not only spaces but all kind of characters that belong to SpaceSeparator, LineSeparator or ParagraphSeparator caregories. So maybe it was a tab or whatever. Have a look at the remarks section of Char.IsWhiteSpace which is used by String.Trim.
Side-Note: if you don't know if the format is valid you could use DateTime.TryParseExact instead which doesn't raise an exception but returns false if a string could not be parsed to DateTime:
bool couldBeParsed = DateTime.TryParseExact(
_date.Trim(),
"yyyy-MM-dd-HH:mm:ss",
CultureInfo.InvariantCulture,
DateTimeStyles.None,
out dt);

Formatting string dates with String.Format()

Just curious...
So I get that if I convert the string version of the date to a DateTime object and pass it into the String.Format() method, then I"ll get the desired results.
String.Format("The date is {0:MMMM dd, yyyy}", DateTime.Parse("05-22-2012"));
"The date is May 22, 2012"
But why doesn't this work?
String.Format("The date is {0:MMMM dd, yyyy}", "05-22-2012")
"The date is 05-22-2012"
Sorry if this is a stupid question, but I'm just trying to understand how this works.
Thanks

The other answers here hit on salient points, but let's put them all together an examine how String.Format works.
It has five overloads, but we're going to talk only about the one that they all redirect to (this is not the actual code, if you want to see it with Reflector or ILSpy, you will find it in StringBuilder.AppendFormat). This is simplified for easy understanding.
public static string Format(IFormatProvider provider, string format, params object[] args)
{
StringBuilder sb = new StringBuilder();
// Break up the format string into an array of tokens
Token[] tokens = ParseFormatString(format);
foreach (Token token in tokens)
{
switch (token.TokenType)
{
// A Text token is just some text to output directly
case TokenType.Text:
sb.Append(token.Text);
break;
// An Index token represents something like {0} or {2:format}
// token.Index is the argument index
// token.FormatText is the format string inside ('' in the first example, 'format' in the second example)
case TokenType.Index:
{
object arg = args[token.Index];
IFormattable formattable = arg as IFormattable;
if (formattable != null && token.FormatText.Length > 0)
{
// If the argument is IFormattable we pass it the format string specified with the index
sb.Append(formattable.ToString(token.FormatText, provider));
}
else
{
// Otherwise we just use Object.ToString
sb.Append(arg.ToString());
}
}
break;
}
}
return sb.ToString();
}
In your question you ask why the format string doesn't get applied when you pass "05-22-2012". As Guffa said, that is not a DateTime object, it is a String object.
As GSerjo said, a String is not IFormattable. Strings are not formattable because formatting is the process of converting something into a String. A string is already a string!
So you can see that when the Format method gets to indexer, arg will not be IFormattable and it will simply call ToString. Calling ToString on a string simply returns itself, it's already a string.
In summary, if your format string contains an index with an inner-format string (e.g. {0:format}), that inner-format string will only be applied if the associated argument is IFormattable and it knows what to do with the format string you give it.

A custom datetime format only works on a DateTime value. If you are using a string instead, the format will be ignored because there is only one way to output a string.

Because "05-22-2012" is not IFormattable, DateTime.Parse("05-22-2012") it's DateTime
please look here for more examples
String Format for DateTime
Custom Date and Time Format Strings