We Keep Coding

convert to double 5.55111512312578E-17

How to convert -5.55111512312578E-17 to 5.55?
my code:
var value=reader11["PendingQty"].ToString().Replace('-', ' ');
var a=String.Format("{0:0.00}", value);
i also Tried : value= Math.round

-5.55111512312578E-17 is equal to 0.0000000000000000555111512312578. You could get this value by doing this:
double output = Double.Parse(input, System.Globalization.NumberStyles.Float, System.Globalization.CultureInfo.InvariantCulture);
Console.WriteLine(output.ToString("F99").TrimEnd('0'));
But as far as I understood, you actually only want to first three digits, so I would do a string manipulation:
input.Substring(1,4);
This takes 4 characters, starting at the second position. If you have positive values too, simply check and read from the first digit on:
var res = "";
if (input.StartsWith("-")) {
res = input.Substring(1,4));
}
else {
res = input.Substring(0,4);
}

Convert string to decimal but keep numeric portion

Is there a way to convert a string to decimal in C# but ignoring trailing "garbage"? i.e. like PHP's floatval() or C strtod() ?
e.g.
Convert string "2974.23abcdefs" to decimal 2974.23

As others have mentioned, there is no exact, like for like, replacement for what you can do in PHP and I think, for good reason. In the scenario of a web application, I'm not really sure that if I were accepting a decimal with garbage at the end, I'd actually want to consider that as valid data but this is just my opinion.
What you can do is define a regular expression that would capture the decimal and recognise that this is happening. I find this much safer and reliable.
Obviously, the regular expression can be improved but this is a simple example for you: -
var match = Regex.Match("2974.23abcdefs", "^([0-9]+\\.[0-9]+)(.+)?$");
if (match.Success)
{
// See the also the link below for using Decimal.TryParse
Console.WriteLine(Convert.ToDecimal(match.Groups[1].Value));
}
See https://msdn.microsoft.com/en-us/library/system.decimal.tryparse%28v=vs.110%29.aspx for my preferred way to convert to a decimal. This would ensure that you are coping with the output of the regular expression for how Decimal is comprised
For more information on regular expressions, see https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex%28v=vs.110%29.aspx

This works but only takes care of digits and the current culture's decimal-separator:
string input = "2974.23abcdefs";
decimal d;
char decSep = NumberFormatInfo.CurrentInfo.NumberDecimalSeparator[0]; // there is no culture with a decimal-separator that has more than one letter so this isn't harmful
if(!string.IsNullOrEmpty(input) && Char.IsDigit(input[0]))
{
string number = string.Concat(input.TakeWhile(c => Char.IsDigit(c) || decSep == c));
bool validDecimal = decimal.TryParse(number, out d);
Console.WriteLine("Valid? {0} Parsed to: {1}", validDecimal, d);
}
Since we are using , as decimal separator here in germany i get a different result than people who use . as separator. You get 2974.23 and i get 2974.

As a first, second, third try, this should go:
static double Parse(string str, IFormatProvider provider = null)
{
if (str == string.Empty)
{
return 0;
}
if (provider == null)
{
provider = CultureInfo.CurrentCulture;
}
NumberFormatInfo nfi = NumberFormatInfo.GetInstance(provider);
// [ws][sign][integral-digits[,]]integral-digits[.[fractional-digits]][E[sign]exponential-digits][ws]
string ws = #"\s*";
string sign = #"(" + Regex.Escape(nfi.PositiveSign) + "|" + Regex.Escape(nfi.NegativeSign) + ")?";
string integralDigits1 = "([0-9](" + Regex.Escape(nfi.NumberGroupSeparator) + ")*)*";
string integralDigits2 = "[0-9]+";
string fractionalDigits = "(" + Regex.Escape(nfi.NumberDecimalSeparator) + "[0-9]*)?";
string exponentialDigits = "([Ee]" + sign + "[0-9]+)?";
var rx = new Regex(ws + sign + integralDigits1 + integralDigits2 + fractionalDigits + exponentialDigits);
string match = rx.Match(str).ToString();
if (match == string.Empty)
{
return 0;
}
return double.Parse(match, provider);
}
Note that the composed regex is very complex, because there are various "parts" in a full double that has been written to a string.
From MSDN:
[ws][sign][integral-digits[,]]integral-digits[.[fractional-digits]][E[sign]exponential-digits][ws]
Still some numbers will crash this function, if they are too much big. So passing new string('9', 1000) will make the double.Parse throw an exception.
Use it like:
double num = Parse(" +1,0.1234E+12abcdefgh", CultureInfo.InvariantCulture);
or
double num = Parse(" +1,,,,,0.1234E+12abcdefgh");
(if you don't need to configure the culture, will use the CultureInfo.CurrentCulture)

There are many ways to do so. I suggest using a Regex first, and then decimal.TryParse().
This is a regex that grabs a floating point number at the begin of the string, like -123.43 or just 1234.56 or 123456:
^([+-][0-9]+\.?[0-9]*).*$
Putting this into C# looks like this:
// Step 1: Getting some input
String input = "123.4533wefwe";
// Step 2: Get rid of the trail
Regex r = new Regex(#"^([+-][0-9]+\.?[0-9]*).*$", RegexOptions.IgnoreCase);
MatchCollection matches = r.Matches(input);
if (matches.Count > 0) {
Match match = matches[0];
GroupCollection groups = match.Groups;
// Step 3: create a real decimal from the string
decimal i;
NumberStyles style;
CultureInfo culture;
style = NumberStyles.Number;
culture = CultureInfo.CreateSpecificCulture("en-GB");
String matchedNumber = groups[1].Value;
if (decimal.TryParse(matchedNumber, style, culture, out i)) {
// Step 4: giving back the result:
Console.WriteLine("Parsed decimal: " + i);
}
}
The output of this is:
Parsed decimal: 123.4533
Remark: All this seems to become a bigger problem if you would like to parse real floating point number literals that include exponential notation. Then, severals stages of casting would be necessary.

Parse string and return only the information between bracket symbols. C# Winforms

I would like to parse a string to return only a value that is in between bracket symbols, such as [10.2%]. Then I would need to strip the "%" symbol and convert the decimal to a rounded up/down integer. So, [10.2%] would end up being 10. And, [11.8%] would end up being 12.
Hopefully I have provided sufficient information.

Math.Round(
double.Parse(
"[11.8%]".Split(new [] {"[", "]", "%"},
StringSplitOptions.RemoveEmptyEntries)[0]))

Why not use Regex?
In this example, I am assuming that your value inside the brackets always are a double with decimals.
string WithBrackets = "[11.8%]";
string AsDouble = Regex.Match(WithBrackets, "\d{1,9}\.\d{1,9}").value;
int Out = Math.Round(Convert.ToDouble(AsDouble.replace(".", ","));

var s = "[10.2%]";
var numberString = s.Split(new char[] {'[',']','%'},StringSplitOptions.RemoveEmptyEntries).First();
var number = Math.Round(Covnert.ToDouble(numberString));

If you can ensure that the content between the brackets is of the form <decimal>%, then this little function will return the value between the fist set of brackets. If there are more than one values you need to extract then you will need to modify it somewhat.
public decimal getProp(string str)
{
int obIndex = str.IndexOf("["); // get the index of the open bracket
int cbIndex = str.IndexOf("]"); // get the index of the close bracket
decimal d = decimal.Parse(str.Substring(obIndex + 1, cbIndex - obIndex - 2)); // this extracts the numerical part and converts it to a decimal (assumes a % before the ])
return Math.Round(d); // return the number rounded to the nearest integer
}
For example getProp("I like cookies [66.7%]") gives the Decimal number 67

Use regular expressions (Regex) to find the required words within one bracket.
This is the code you need:
Use an foreach loop to remove the % and convert to int.
List<int> myValues = new List<int>();
foreach(string s in Regex.Match(MYTEXT, #"\[(?<tag>[^\]]*)\]")){
s = s.TrimEnd('%');
myValues.Add(Math.Round(Convert.ToDouble(s)));
}

How can I parse the int from a String in C#?

I have a string that contains an int. How can I parse the int in C#?
Suppose I have the following strings, which contains an integer:
15 person
person 15
person15
15person
How can I track them, or return null if no integer is found in the string?

You can remove all non-digits, and parse the string if there is anything left:
str = Regex.Replace(str, "\D+", String.Empty);
if (str.Length > 0) {
int value = Int32.Parse(str);
// here you can use the value
}

Paste this code into a test:
public int? ParseAnInt(string s)
{
var match = System.Text.RegularExpressions.Regex.Match(s, #"\d+");
if (match.Success)
{
int result;
//still use TryParse to handle integer overflow
if (int.TryParse(match.Value, out result))
return result;
}
return null;
}
[TestMethod]
public void TestThis()
{
Assert.AreEqual(15, ParseAnInt("15 person"));
Assert.AreEqual(15, ParseAnInt("person 15"));
Assert.AreEqual(15, ParseAnInt("person15"));
Assert.AreEqual(15, ParseAnInt("15person"));
Assert.IsNull(ParseAnInt("nonumber"));
}
The method returns null is no number is found - it also handles the case where the number causes an integer overflow.
To reduce the chance of an overflow you could instead use long.TryParse
Equally if you anticipate multiple groups of digits, and you want to parse each group as a discreet number you could use Regex.Matches - which will return an enumerable of all the matches in the input string.

Use something like this :
Regex r = new Regex("\d+");
Match m = r.Match(yourinputstring);
if(m.Success)
{
Dosomethingwiththevalue(m.Value);
}

Since everyone uses Regex to extract the numbers, here's a Linq way to do it:
string input = "15person";
string numerics = new string(input.Where(Char.IsDigit).ToArray());
int result = int.Parse(numerics);
Just for the sake of completeness, it's probably not overly elegant. Regarding Jaymz' comment, this would return 151314 when 15per13so14n is passed.

string manipulation check and replace with fastest method

I have some strings like below:
string num1 = "D123_1";
string num2 = "D123_2";
string num3 = "D456_11";
string num4 = "D456_22";
string num5 = "D_123_D";
string num5 = "_D_123";
I want to make a function that will do the following actions:
1- Checks if given string DOES HAVE an Underscore in it, and this underscore should be after some Numbers and Follow with some numbers: in this case 'num5' and 'num6' are invalid!
2- Replace the numbers after the last underscore with any desired string, for example I want 'num1 = "D123_1"' to be changed into 'D123_2'
So far I came with this idea but it is not working :( First I dont know how to check for criteria 1 and second the replace statement is not working:
private string CheckAndReplace(string given, string toAdd)
{
var changedString = given.Split('_');
return changedString[changedString.Length - 1] + toAdd;
}
Any help and tips will be appriciated

What you are looking for is a regular expression. This is (mostly) from the top of my head. But it should easily point you in the right direction. The regular expression works fine.
public static Regex regex = new Regex("(?<character>[a-zA-Z]+)(?<major>\\d+)_(?<minor>\\d+)",RegexOptions.CultureInvariant | RegexOptions.Compiled);
Match m = regex.Match(InputText);
if (m.Succes)
{
var newValue = String.Format("{0}{1}_{2}"m.Groups["character"].Value, m.Groups["major"].Value, m.Groups["minor"].Value);
}

In your code you split the String into an array of strings and then access the wrong index of the array, so it isn't doing what you want.
Try working with a substring instead. Find the index of the last '_' and then get the substring:
private string CheckAndReplace(string given, string toAdd) {
int index = given.LastIndexOf('_')+1;
return given.Substring(0,index) + toAdd;
}
But before that check the validity of the string (see other answers). This code fragment will break when there's no '_' in the string.

You could use a regular expression (this is not a complete implementation, only a hint):
private string CheckAndReplace(string given, string toAdd)
{
Regex regex = new Regex("([A-Z]*[0-9]+_)[0-9]+");
if (regex.IsMatch(given))
{
return string.Concat(regex.Match(given).Groups[1].Value, toAdd);
}
else
{
... do something else
}
}

Use a good regular expression implementation. .NET has standard implementation of them