I have a number (just an example:
"3616,946489653802082229919075063226"
stored in a string. I want to convert it into decimal but get an OverflowException because the value is too long for decimal.
I want to round the string before converting it to fix the error.
How do I do this?
Parsing is culture specific. So , can be either decimal or thousand separator. If , is a thousand separator, it will be ignored:
"3616,946489653802082229919075063226" -> 3616946489653802082229919075063226m
And this value is over decimal.MaxValue so you have the exception thrown.
If , should be treated as a decimal separator, let system know it:
decimal result = decimal.Parse(source,
new NumberFormatInfo() { NumberDecimalSeparator = ","});
And you'll get 3616.9464896538020822299190751m
Your problem is not actually a rounding issue, it is trying to parse a decimal with a comma on a system which expects a dot as a decimal separator by default.
You could try this to make sure it is parsed well on all environments:
using System;
using System.Globalization;
public class Program
{
public static void Main()
{
var input = "3616,946489653802082229919075063226";
var result = decimal.Parse(input, new NumberFormatInfo() { NumberDecimalSeparator = ","});
Console.WriteLine(result);
}
}
https://dotnetfiddle.net/8iaL9d
Given an arbitrary number of decimal places in a format with a comma separating the units from the fractional part, you could solve it by doing the following:
class Program
{
static void Main(string[] args)
{
var decimalPlacesCount = 10;
var decimalSeparator = ',';
var parts = "3616,946489653802082229919075063226".Split(decimalSeparator);
var value = decimal.Parse(parts[0]);
if (parts.Length == 2)
{
value += decimal.Parse($"0.{parts[1].Substring(0, decimalPlacesCount)}");
}
Console.WriteLine(value);
}
}
This effectively rounds it to decimalPlacesCount.
While this wasn't your problem if anyone happens to stumble across this well-named question looking for a method that will actually round a string hopefully, the following will be helpful.
public static string RoundString(string value, int decimalPlaces)
{
StringBuilder returnValue = new StringBuilder(value);
int startIndex = 0;
int charIndex = 0;
while (charIndex < value.Length && startIndex == 0)
{
if (value[charIndex].ToString() == ".")
startIndex = charIndex + 1;
charIndex++;
}
if (int.Parse(value[charIndex + decimalPlaces + 1].ToString()) >= 5)
{
bool rounded = false;
for (charIndex = startIndex + decimalPlaces; charIndex > -1; charIndex--)
{
if (!rounded && charIndex != startIndex-1)
{
int newVal = int.Parse(returnValue[charIndex].ToString()) + 1;
if (newVal > 9)
{
returnValue[charIndex] = '0';
}
else
{
returnValue[charIndex] = (int.Parse(returnValue[charIndex].ToString()) + 1).ToString()[0];
rounded = true;
}
}
}
if (!rounded)
{
startIndex++;
returnValue = new StringBuilder("1" + returnValue.ToString());
}
}
return returnValue.ToString().Substring(0, startIndex + decimalPlaces);
}
It's pretty poorly written and I'm sure someone could do better, but it does the job. The StringBuilder is pretty shoddy for example and it can likely be made to run quicker.
Also, I do 0 validation on the actual input string.
How to convert a double into a floating-point string representation without scientific notation in the .NET Framework?
"Small" samples (effective numbers may be of any size, such as 1.5E200 or 1e-200) :
3248971234698200000000000000000000000000000000
0.00000000000000000000000000000000000023897356978234562
None of the standard number formats are like this, and a custom format also doesn't seem to allow having an open number of digits after the decimal separator.
This is not a duplicate of How to convert double to string without the power to 10 representation (E-05) because the answers given there do not solve the issue at hand. The accepted solution in this question was to use a fixed point (such as 20 digits), which is not what I want. A fixed point formatting and trimming the redundant 0 doesn't solve the issue either because the max width for fixed width is 99 characters.
Note: the solution has to deal correctly with custom number formats (e.g. other decimal separator, depending on culture information).
Edit: The question is really only about displaing aforementioned numbers. I'm aware of how floating point numbers work and what numbers can be used and computed with them.
For a general-purpose¹ solution you need to preserve 339 places:
doubleValue.ToString("0." + new string('#', 339))
The maximum number of non-zero decimal digits is 16. 15 are on the right side of the decimal point. The exponent can move those 15 digits a maximum of 324 places to the right. (See the range and precision.)
It works for double.Epsilon, double.MinValue, double.MaxValue, and anything in between.
The performance will be much greater than the regex/string manipulation solutions since all formatting and string work is done in one pass by unmanaged CLR code. Also, the code is much simpler to prove correct.
For ease of use and even better performance, make it a constant:
public static class FormatStrings
{
public const string DoubleFixedPoint = "0.###################################################################################################################################################################################################################################################################################################################################################";
}
¹ Update: I mistakenly said that this was also a lossless solution. In fact it is not, since ToString does its normal display rounding for all formats except r. Live example. Thanks, #Loathing! Please see Lothing’s answer if you need the ability to roundtrip in fixed point notation (i.e, if you’re using .ToString("r") today).
I had a similar problem and this worked for me:
doubleValue.ToString("F99").TrimEnd('0')
F99 may be overkill, but you get the idea.
This is a string parsing solution where the source number (double) is converted into a string and parsed into its constituent components. It is then reassembled by rules into the full-length numeric representation. It also accounts for locale as requested.
Update: The tests of the conversions only include single-digit whole numbers, which is the norm, but the algorithm also works for something like: 239483.340901e-20
using System;
using System.Text;
using System.Globalization;
using System.Threading;
public class MyClass
{
public static void Main()
{
Console.WriteLine(ToLongString(1.23e-2));
Console.WriteLine(ToLongString(1.234e-5)); // 0.00010234
Console.WriteLine(ToLongString(1.2345E-10)); // 0.00000001002345
Console.WriteLine(ToLongString(1.23456E-20)); // 0.00000000000000000100023456
Console.WriteLine(ToLongString(5E-20));
Console.WriteLine("");
Console.WriteLine(ToLongString(1.23E+2)); // 123
Console.WriteLine(ToLongString(1.234e5)); // 1023400
Console.WriteLine(ToLongString(1.2345E10)); // 1002345000000
Console.WriteLine(ToLongString(-7.576E-05)); // -0.00007576
Console.WriteLine(ToLongString(1.23456e20));
Console.WriteLine(ToLongString(5e+20));
Console.WriteLine("");
Console.WriteLine(ToLongString(9.1093822E-31)); // mass of an electron
Console.WriteLine(ToLongString(5.9736e24)); // mass of the earth
Console.ReadLine();
}
private static string ToLongString(double input)
{
string strOrig = input.ToString();
string str = strOrig.ToUpper();
// if string representation was collapsed from scientific notation, just return it:
if (!str.Contains("E")) return strOrig;
bool negativeNumber = false;
if (str[0] == '-')
{
str = str.Remove(0, 1);
negativeNumber = true;
}
string sep = Thread.CurrentThread.CurrentCulture.NumberFormat.NumberDecimalSeparator;
char decSeparator = sep.ToCharArray()[0];
string[] exponentParts = str.Split('E');
string[] decimalParts = exponentParts[0].Split(decSeparator);
// fix missing decimal point:
if (decimalParts.Length==1) decimalParts = new string[]{exponentParts[0],"0"};
int exponentValue = int.Parse(exponentParts[1]);
string newNumber = decimalParts[0] + decimalParts[1];
string result;
if (exponentValue > 0)
{
result =
newNumber +
GetZeros(exponentValue - decimalParts[1].Length);
}
else // negative exponent
{
result =
"0" +
decSeparator +
GetZeros(exponentValue + decimalParts[0].Length) +
newNumber;
result = result.TrimEnd('0');
}
if (negativeNumber)
result = "-" + result;
return result;
}
private static string GetZeros(int zeroCount)
{
if (zeroCount < 0)
zeroCount = Math.Abs(zeroCount);
StringBuilder sb = new StringBuilder();
for (int i = 0; i < zeroCount; i++) sb.Append("0");
return sb.ToString();
}
}
You could cast the double to decimal and then do ToString().
(0.000000005).ToString() // 5E-09
((decimal)(0.000000005)).ToString() // 0,000000005
I haven't done performance testing which is faster, casting from 64-bit double to 128-bit decimal or a format string of over 300 chars. Oh, and there might possibly be overflow errors during conversion, but if your values fit a decimal this should work fine.
Update: The casting seems to be a lot faster. Using a prepared format string as given in the other answer, formatting a million times takes 2.3 seconds and casting only 0.19 seconds. Repeatable. That's 10x faster. Now it's only about the value range.
This is what I've got so far, seems to work, but maybe someone has a better solution:
private static readonly Regex rxScientific = new Regex(#"^(?<sign>-?)(?<head>\d+)(\.(?<tail>\d*?)0*)?E(?<exponent>[+\-]\d+)$", RegexOptions.IgnoreCase|RegexOptions.ExplicitCapture|RegexOptions.CultureInvariant);
public static string ToFloatingPointString(double value) {
return ToFloatingPointString(value, NumberFormatInfo.CurrentInfo);
}
public static string ToFloatingPointString(double value, NumberFormatInfo formatInfo) {
string result = value.ToString("r", NumberFormatInfo.InvariantInfo);
Match match = rxScientific.Match(result);
if (match.Success) {
Debug.WriteLine("Found scientific format: {0} => [{1}] [{2}] [{3}] [{4}]", result, match.Groups["sign"], match.Groups["head"], match.Groups["tail"], match.Groups["exponent"]);
int exponent = int.Parse(match.Groups["exponent"].Value, NumberStyles.Integer, NumberFormatInfo.InvariantInfo);
StringBuilder builder = new StringBuilder(result.Length+Math.Abs(exponent));
builder.Append(match.Groups["sign"].Value);
if (exponent >= 0) {
builder.Append(match.Groups["head"].Value);
string tail = match.Groups["tail"].Value;
if (exponent < tail.Length) {
builder.Append(tail, 0, exponent);
builder.Append(formatInfo.NumberDecimalSeparator);
builder.Append(tail, exponent, tail.Length-exponent);
} else {
builder.Append(tail);
builder.Append('0', exponent-tail.Length);
}
} else {
builder.Append('0');
builder.Append(formatInfo.NumberDecimalSeparator);
builder.Append('0', (-exponent)-1);
builder.Append(match.Groups["head"].Value);
builder.Append(match.Groups["tail"].Value);
}
result = builder.ToString();
}
return result;
}
// test code
double x = 1.0;
for (int i = 0; i < 200; i++) {
x /= 10;
}
Console.WriteLine(x);
Console.WriteLine(ToFloatingPointString(x));
The problem using #.###...### or F99 is that it doesn't preserve precision at the ending decimal places, e.g:
String t1 = (0.0001/7).ToString("0." + new string('#', 339)); // 0.0000142857142857143
String t2 = (0.0001/7).ToString("r"); // 1.4285714285714287E-05
The problem with DecimalConverter.cs is that it is slow. This code is the same idea as Sasik's answer, but twice as fast. Unit test method at bottom.
public static class RoundTrip {
private static String[] zeros = new String[1000];
static RoundTrip() {
for (int i = 0; i < zeros.Length; i++) {
zeros[i] = new String('0', i);
}
}
private static String ToRoundTrip(double value) {
String str = value.ToString("r");
int x = str.IndexOf('E');
if (x < 0) return str;
int x1 = x + 1;
String exp = str.Substring(x1, str.Length - x1);
int e = int.Parse(exp);
String s = null;
int numDecimals = 0;
if (value < 0) {
int len = x - 3;
if (e >= 0) {
if (len > 0) {
s = str.Substring(0, 2) + str.Substring(3, len);
numDecimals = len;
}
else
s = str.Substring(0, 2);
}
else {
// remove the leading minus sign
if (len > 0) {
s = str.Substring(1, 1) + str.Substring(3, len);
numDecimals = len;
}
else
s = str.Substring(1, 1);
}
}
else {
int len = x - 2;
if (len > 0) {
s = str[0] + str.Substring(2, len);
numDecimals = len;
}
else
s = str[0].ToString();
}
if (e >= 0) {
e = e - numDecimals;
String z = (e < zeros.Length ? zeros[e] : new String('0', e));
s = s + z;
}
else {
e = (-e - 1);
String z = (e < zeros.Length ? zeros[e] : new String('0', e));
if (value < 0)
s = "-0." + z + s;
else
s = "0." + z + s;
}
return s;
}
private static void RoundTripUnitTest() {
StringBuilder sb33 = new StringBuilder();
double[] values = new [] { 123450000000000000.0, 1.0 / 7, 10000000000.0/7, 100000000000000000.0/7, 0.001/7, 0.0001/7, 100000000000000000.0, 0.00000000001,
1.23e-2, 1.234e-5, 1.2345E-10, 1.23456E-20, 5E-20, 1.23E+2, 1.234e5, 1.2345E10, -7.576E-05, 1.23456e20, 5e+20, 9.1093822E-31, 5.9736e24, double.Epsilon };
foreach (int sign in new [] { 1, -1 }) {
foreach (double val in values) {
double val2 = sign * val;
String s1 = val2.ToString("r");
String s2 = ToRoundTrip(val2);
double val2_ = double.Parse(s2);
double diff = Math.Abs(val2 - val2_);
if (diff != 0) {
throw new Exception("Value {0} did not pass ToRoundTrip.".Format2(val.ToString("r")));
}
sb33.AppendLine(s1);
sb33.AppendLine(s2);
sb33.AppendLine();
}
}
}
}
The obligatory Logarithm-based solution. Note that this solution, because it involves doing math, may reduce the accuracy of your number a little bit. Not heavily tested.
private static string DoubleToLongString(double x)
{
int shift = (int)Math.Log10(x);
if (Math.Abs(shift) <= 2)
{
return x.ToString();
}
if (shift < 0)
{
double y = x * Math.Pow(10, -shift);
return "0.".PadRight(-shift + 2, '0') + y.ToString().Substring(2);
}
else
{
double y = x * Math.Pow(10, 2 - shift);
return y + "".PadRight(shift - 2, '0');
}
}
Edit: If the decimal point crosses non-zero part of the number, this algorithm will fail miserably. I tried for simple and went too far.
In the old days when we had to write our own formatters, we'd isolate the mantissa and exponent and format them separately.
In this article by Jon Skeet (https://csharpindepth.com/articles/FloatingPoint) he provides a link to his DoubleConverter.cs routine that should do exactly what you want. Skeet also refers to this at extracting mantissa and exponent from double in c#.
I have just improvised on the code above to make it work for negative exponential values.
using System;
using System.Text.RegularExpressions;
using System.IO;
using System.Text;
using System.Threading;
namespace ConvertNumbersInScientificNotationToPlainNumbers
{
class Program
{
private static string ToLongString(double input)
{
string str = input.ToString(System.Globalization.CultureInfo.InvariantCulture);
// if string representation was collapsed from scientific notation, just return it:
if (!str.Contains("E")) return str;
var positive = true;
if (input < 0)
{
positive = false;
}
string sep = Thread.CurrentThread.CurrentCulture.NumberFormat.NumberDecimalSeparator;
char decSeparator = sep.ToCharArray()[0];
string[] exponentParts = str.Split('E');
string[] decimalParts = exponentParts[0].Split(decSeparator);
// fix missing decimal point:
if (decimalParts.Length == 1) decimalParts = new string[] { exponentParts[0], "0" };
int exponentValue = int.Parse(exponentParts[1]);
string newNumber = decimalParts[0].Replace("-", "").
Replace("+", "") + decimalParts[1];
string result;
if (exponentValue > 0)
{
if (positive)
result =
newNumber +
GetZeros(exponentValue - decimalParts[1].Length);
else
result = "-" +
newNumber +
GetZeros(exponentValue - decimalParts[1].Length);
}
else // negative exponent
{
if (positive)
result =
"0" +
decSeparator +
GetZeros(exponentValue + decimalParts[0].Replace("-", "").
Replace("+", "").Length) + newNumber;
else
result =
"-0" +
decSeparator +
GetZeros(exponentValue + decimalParts[0].Replace("-", "").
Replace("+", "").Length) + newNumber;
result = result.TrimEnd('0');
}
float temp = 0.00F;
if (float.TryParse(result, out temp))
{
return result;
}
throw new Exception();
}
private static string GetZeros(int zeroCount)
{
if (zeroCount < 0)
zeroCount = Math.Abs(zeroCount);
StringBuilder sb = new StringBuilder();
for (int i = 0; i < zeroCount; i++) sb.Append("0");
return sb.ToString();
}
public static void Main(string[] args)
{
//Get Input Directory.
Console.WriteLine(#"Enter the Input Directory");
var readLine = Console.ReadLine();
if (readLine == null)
{
Console.WriteLine(#"Enter the input path properly.");
return;
}
var pathToInputDirectory = readLine.Trim();
//Get Output Directory.
Console.WriteLine(#"Enter the Output Directory");
readLine = Console.ReadLine();
if (readLine == null)
{
Console.WriteLine(#"Enter the output path properly.");
return;
}
var pathToOutputDirectory = readLine.Trim();
//Get Delimiter.
Console.WriteLine("Enter the delimiter;");
var columnDelimiter = (char)Console.Read();
//Loop over all files in the directory.
foreach (var inputFileName in Directory.GetFiles(pathToInputDirectory))
{
var outputFileWithouthNumbersInScientificNotation = string.Empty;
Console.WriteLine("Started operation on File : " + inputFileName);
if (File.Exists(inputFileName))
{
// Read the file
using (var file = new StreamReader(inputFileName))
{
string line;
while ((line = file.ReadLine()) != null)
{
String[] columns = line.Split(columnDelimiter);
var duplicateLine = string.Empty;
int lengthOfColumns = columns.Length;
int counter = 1;
foreach (var column in columns)
{
var columnDuplicate = column;
try
{
if (Regex.IsMatch(columnDuplicate.Trim(),
#"^[+-]?[0-9]+(\.[0-9]+)?[E]([+-]?[0-9]+)$",
RegexOptions.IgnoreCase))
{
Console.WriteLine("Regular expression matched for this :" + column);
columnDuplicate = ToLongString(Double.Parse
(column,
System.Globalization.NumberStyles.Float));
Console.WriteLine("Converted this no in scientific notation " +
"" + column + " to this number " +
columnDuplicate);
}
}
catch (Exception)
{
}
duplicateLine = duplicateLine + columnDuplicate;
if (counter != lengthOfColumns)
{
duplicateLine = duplicateLine + columnDelimiter.ToString();
}
counter++;
}
duplicateLine = duplicateLine + Environment.NewLine;
outputFileWithouthNumbersInScientificNotation = outputFileWithouthNumbersInScientificNotation + duplicateLine;
}
file.Close();
}
var outputFilePathWithoutNumbersInScientificNotation
= Path.Combine(pathToOutputDirectory, Path.GetFileName(inputFileName));
//Create Directory If it does not exist.
if (!Directory.Exists(pathToOutputDirectory))
Directory.CreateDirectory(pathToOutputDirectory);
using (var outputFile =
new StreamWriter(outputFilePathWithoutNumbersInScientificNotation))
{
outputFile.Write(outputFileWithouthNumbersInScientificNotation);
outputFile.Close();
}
Console.WriteLine("The transformed file is here :" +
outputFilePathWithoutNumbersInScientificNotation);
}
}
}
}
}
This code takes an input directory and based on the delimiter converts all values in scientific notation to numeric format.
Thanks
try this one:
public static string DoubleToFullString(double value,
NumberFormatInfo formatInfo)
{
string[] valueExpSplit;
string result, decimalSeparator;
int indexOfDecimalSeparator, exp;
valueExpSplit = value.ToString("r", formatInfo)
.ToUpper()
.Split(new char[] { 'E' });
if (valueExpSplit.Length > 1)
{
result = valueExpSplit[0];
exp = int.Parse(valueExpSplit[1]);
decimalSeparator = formatInfo.NumberDecimalSeparator;
if ((indexOfDecimalSeparator
= valueExpSplit[0].IndexOf(decimalSeparator)) > -1)
{
exp -= (result.Length - indexOfDecimalSeparator - 1);
result = result.Replace(decimalSeparator, "");
}
if (exp >= 0) result += new string('0', Math.Abs(exp));
else
{
exp = Math.Abs(exp);
if (exp >= result.Length)
{
result = "0." + new string('0', exp - result.Length)
+ result;
}
else
{
result = result.Insert(result.Length - exp, decimalSeparator);
}
}
}
else result = valueExpSplit[0];
return result;
}
Being millions of programmers world wide, it's always a good practice to try search if someone has bumped into your problem already. Sometimes there's solutions are garbage, which means it's time to write your own, and sometimes there are great, such as the following:
http://www.yoda.arachsys.com/csharp/DoubleConverter.cs
(details: http://www.yoda.arachsys.com/csharp/floatingpoint.html)
string strdScaleFactor = dScaleFactor.ToString(); // where dScaleFactor = 3.531467E-05
decimal decimalScaleFactor = Decimal.Parse(strdScaleFactor, System.Globalization.NumberStyles.Float);
I don't know if my answer to the question can still be helpful. But in this case I suggest the "decomposition of the double variable into decimal places" to store it in an Array / Array of data of type String.
This process of decomposition and storage in parts (number by number) from double to string, would basically work with the use of two loops and an "alternative" (if you thought of workaround, I think you got it), where the first loop will extract the values from double without converting to String, resulting in blessed scientific notation and storing number by number in an Array. And this will be done using MOD - the same method to check a palindrome number, which would be for example:
String[] Array_ = new double[ **here you will put an extreme value of places your DOUBLE can reach, you must have a prediction**];
for (int i = 0, variableDoubleMonstrous > 0, i++){
x = variableDoubleMonstrous %10;
Array_[i] = x;
variableDoubleMonstrous /= 10;
}
And the second loop to invert the Array values (because in this process of checking a palindrome, the values invert from the last place, to the first, from the penultimate to the second and so on. Remember?) to get the original value:
String[] ArrayFinal = new String[the same number of "places" / indices of the other Array / Data array];
int lengthArray = Array_.Length;
for (int i = 0, i < Array_.Length, i++){
FinalArray[i] = Array_[lengthArray - 1];
lengthArray--;
}
***Warning: There's a catch that I didn't pay attention to. In that case there will be no "." (floating point decimal separator or double), so this solution is not generalized. But if it is really important to use decimal separators, unfortunately the only possibility (If done well, it will have a great performance) is:
**Use a routine to get the position of the decimal point of the original value, the one with scientific notation - the important thing is that you know that this floating point is before a number such as the "Length" position x, and after a number such as the y position - extracting each digit using the loops - as shown above - and at the end "export" the data from the last Array to another one, including the decimal place divider (the comma, or the period , if variable decimal, double or float) in the imaginary position that was in the original variable, in the "real" position of that matrix.
*** The concept of position is, find out how many numbers occur before the decimal point, so with this information you will be able to store in the String Array the point in the real position.
NEEDS THAT CAN BE MADE:
But then you ask:
But what about when I'm going to convert String to a floating point value?
My answer is that you use the second matrix of this entire process (the one that receives the inversion of the first matrix that obtains the numbers by the palindrome method) and use it for the conversion, but always making sure, when necessary, of the position of the decimal place in future situations, in case this conversion (Double -> String) is needed again.
But what if the problem is to use the value of the converted Double (Array of Strings) in a calculation. Then in this case you went around in circles. Well, the original variable will work anyway even with scientific notation. The only difference between floating point and decimal variable types is in the rounding of values, which depending on the purpose, it will only be necessary to change the type of data used, but it is dangerous to have a significant loss of information, look here
I could be wrong, but isn't it like this?
data.ToString("n");
http://msdn.microsoft.com/en-us/library/dwhawy9k.aspx
i think you need only to use IFormat with
ToString(doubleVar, System.Globalization.NumberStyles.Number)
example:
double d = double.MaxValue;
string s = d.ToString(d, System.Globalization.NumberStyles.Number);
My solution was using the custom formats.
try this:
double d;
d = 1234.12341234;
d.ToString("#########0.#########");
Just to build on what jcasso said what you can do is to adjust your double value by changing the exponent so that your favorite format would do it for you, apply the format, and than pad the result with zeros to compensate for the adjustment.
This works fine for me...
double number = 1.5E+200;
string s = number.ToString("#");
//Output: "150000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
I am trying to make a simple calculator with arrays in C#. Firstly I tried making it using two integers and one operator only and it worked well. Now I am trying to do so that the user can make the expression as long as they like. For example 7 * 7 + 1 / 50 instead of a simple 9 + 8 which includes only one operator and two integers. The problem is that whenever I type a long expression with multiple numbers and operators it only calculates the first 2 numbers with the first operator. What is a good fix for this problem ? Thanks in advance.
static void Main()
{
while (true)
{
Console.WriteLine("Write an expression with two numbers and an operator with space in-between, for example, 4 + 2");
string expression;
string[] array;
string[] array1;
expression = Console.ReadLine();
array = expression.Split();
array1 = Calculation(array);
Console.WriteLine("Press ENTER to write a new expression.");
Console.ReadLine();
Console.Clear();
}
}
static string[] Calculation(string[] arr)
{
double numLeft= 0.0;
double numRight = 0.0;
string sign = "";
double result = 0.0;
int index = 1;
while (true)
{
numLeft = Convert.ToDouble(arr[0]);
sign = Convert.ToString(arr[index]);
numRight = Convert.ToDouble(arr[index + 1]);
index = index + 2;
if (sign == "+")
{
Console.Clear();
Console.WriteLine();
result= result + numLeft;
}
else if (sign == "-")
{
Console.Clear();
result = result + numLeft;
numLeft = 0 - numRight;
}
else if (sign == "*")
{
Console.Clear();
numLeft = numLeft * numRight;
}
else if (sign == "/")
{
Console.Clear();
numLeft = numLeft / numRight;
}
else
{
break;
}
result = result + numLeft;
Console.WriteLine("Answer: {0}", result);
return arr;
}
return arr;
}
because you return the array at the end of the "while true", so only first 2 get calculated.
Also, this will not be correct. for example: 2 + 3 * 4 = 14, and not 20, like your calculator will calculate.
How about this?
Split your operation string into pieces and fill a list with them;
7 * 7 + 1 / 50 => [7][*][7][+][1][/][50]
Then go through the list and solve the * and / operations. When you encounter one of the operators remove the operator element, the one before it and the one after it, and replace them with the result. Keep in mind that the list length changes.
first iteration => [49][+][1][/][50]
second iteration => [49][+][0.02]
Then do the same for + and - operators
first iteration => [49.02]
When you have only one element remaining in the list, that is your result.
For simple computations there exists a method in .net:
public static int Compute(string operation)
{
return new DataTable().Compute("7 * 7 + 1 / 50", null);
}
Source: C# Math calculator
If you really want to implement this I would suggest a recursive binary tree algorithm.
Pseudo-code:
1. Split incoming string on places where there is a mathematical operation symbol and turn in to a binary tree
2. Go through this tree and resolve operations that have a greater priority (* comes before +)
3. Recursion should return value of two child leafs and so on until it yields only one value to the main program
using System;
namespace _2nd_A_recap
{
class Program
{
static void Main(string[] args)
{
int result;
int a = 20, b = 10;
result = (a + b );
Console.WriteLine("Addition Opertaor:" + result);
result = (a - b);
Console.WriteLine("Subtraction Operator:" + result);
result = (a * b);
Console.WriteLine("Multiplication Operator:" + result);
result = (a / b);
Console.WriteLine("Division Operator:" + result);
result = (a % b);
Console.WriteLine("Modulus Operator:" + result);
Console.WriteLine("Press enter to end Calculator...");
Console.ReadKey();
}
}
}
I need to format a double value to one decimal place without it rounding.
double value = 3.984568438706
string result = "";
What I have tried is:
1)
result = value.ToString("##.##", System.Globalization.CultureInfo.InvariantCulture) + "%";
// returns 3.98%
2)
result = value.ToString("##.#", System.Globalization.CultureInfo.InvariantCulture) + "%";
// returns 4%
3)
result = value.ToString("##.0", System.Globalization.CultureInfo.InvariantCulture) + "%";
// returns 4.0%
4) (Following other suggestions)
value = (value / 100);
result = String.Format("{0:P1}", Math.Truncate(value * 10000) / 10000);
// returns 4.0%
result = string.Format("{0:0.0%}",value); // returns 4.0%
What I need to display is the value 3.9%
Thanks for any help in advance.
result=string.Format("{0:0.0}",Math.Truncate(value*10)/10);
I would make a utility method to handle this:
static double Truncate(double value, int digits)
{
double mult = System.Math.Pow(10.0, digits);
return System.Math.Truncate(value * mult) / mult;
}
You could then do:
result = Truncate(value, 1).ToString("##.#", System.Globalization.CultureInfo.InvariantCulture) + "%";
Note that you may also want Math.Floor instead of truncate - but it depends on how you want negative values handled.
I know this is a old thread but I've just had to do this. While the approaches here work I want a easy way to be able to affect a lot of calls so using the Math.Truncate on all the calls to string.format wasn't really a good option.
Thus, I made a custom format provider which would allow me to add truncation to the formatting string, eg
string.format(new FormatProvider(), "{0:T}", 1.1299); // 1.12
string.format(new FormatProvider(), "{0:T(3)", 1.12399); // 1.123
string.format(new FormatProvider(), "{0:T(1)0,000.0", 1000.9999); // 1,000.9
The implementation is pretty simple and is easily extendible to other requirements.
public class FormatProvider : IFormatProvider, ICustomFormatter
{
public object GetFormat(Type formatType)
{
if (formatType == typeof (ICustomFormatter))
{
return this;
}
return null;
}
public string Format(string format, object arg, IFormatProvider formatProvider)
{
if (arg.GetType() != typeof (double))
{
try
{
return HandleOtherFormats(format, arg);
}
catch (FormatException e)
{
throw new FormatException(string.Format("The format of '{0}' is invalid.", format));
}
}
if (format.StartsWith("T"))
{
int dp = 2;
int idx = 1;
if (format.Length > 1)
{
if (format[1] == '(')
{
int closeIdx = format.IndexOf(')');
if (closeIdx > 0)
{
if (int.TryParse(format.Substring(2, closeIdx - 2), out dp))
{
idx = closeIdx + 1;
}
}
else
{
throw new FormatException(string.Format("The format of '{0}' is invalid.", format));
}
}
}
double mult = Math.Pow(10, dp);
arg = Math.Truncate((double)arg * mult) / mult;
format = format.Substring(idx);
}
try
{
return HandleOtherFormats(format, arg);
}
catch (FormatException e)
{
throw new FormatException(string.Format("The format of '{0}' is invalid.", format));
}
}
private string HandleOtherFormats(string format, object arg)
{
if (arg is IFormattable)
{
return ((IFormattable) arg).ToString(format, CultureInfo.CurrentCulture);
}
return arg != null ? arg.ToString() : String.Empty;
}
}
ToString() doesn't do it. You have to add extra code. The other answers show math approaches, my approach below is kind of outside-the-box.
string result = value.ToString();
Console.WriteLine("{0}", result.Substring(0, result.LastIndexOf('.') + 2));
This is a fairly simple brute force approach, but it does the trick when the decimal is a '.'. Here's an extension method to ease the pain (and deals with the decimal point).
public static class Extensions
{
public static string ToStringNoTruncate(this double me, int decimalplaces = 1)
{
string result = me.ToString();
char dec = System.Globalization.CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator[0];
return result.Substring(0, result.LastIndexOf(dec) + decimalplaces + 1);
}
}
( Math.Truncate( ( value * 10 ) ) / 1000 ).ToString( "#.#%" )
Just use modulo operator + built in ToString:
result = (value - (value % 0.1)).ToString("N1") + "%";
Is there a way to format a double number that always have n digits sepecified by user?
For example if user want to see always 4 digits, take the following numbers as example:
Original Formatted
------- ---------
3.42421 3.424
265.6250 265.6
812.50 812.5
12.68798 12.68
0.68787 0.687
I made up this but it just allows for number of floating points! it is not what I wanted!
public string ToEngV(double d, int percision = 0)
{
string zeros = string.Empty;
if (percision <= 0)
{
zeros += "0";
}
else if (percision > 0)
{
for (int i = 0; i < percision; i++)
{
zeros += "0";
}
}
return String.Format("{0:0." + zeros + "}", d)
}
Imagine I call the above method for a number like 812.50 and I set the precision to (this is now used for all numbers I am going to format). Obviously the output will be 812.5
But if I give the another number like 1.61826 I will get 1.6 and this ruins the formatting in the page I show these number to users. I need that to be 1.618
Thus I want my method to always show N digit!
I'm not sure if your asking to round or truncate numbers, so I wrote this method:
public static string ToEngV(this double d, int digits, bool round)
{
var lenght = Math.Truncate(d).ToString().Length;
if (lenght > digits)
{
throw new ArgumentException("...");
}
int decimals = digits - lenght;
if (round)
{
return Math.Round(d, decimals).ToString();
}
else
{
int pow = (int)Math.Pow(10, decimals);
return (Math.Truncate(d * pow) / pow).ToString();
}
}
Example:
var numbers = new double[] { 3.42421, 265.6250, 812.50, 12.68798, 0.68787 };
foreach (var number in numbers)
{
Console.WriteLine(number.ToEngV(4, false));
}
Console.WriteLine()
foreach (var number in numbers)
{
Console.WriteLine(number.ToEngV(4, true));
}
Output:
3.424
265.6
812.5
12.68
0.687
3.424
265.6
812.5
12.69
0.688
Note that if your number has more integer digits than digits you will get an ArgumentException.
number.ToString("#0.000").Substring(0, 5);
I'm not sure this is what you're searching for, anyway give it a try:
string FmtDbl(double num, int digits)
{
digits++; // To include decimal separator
string ret = num.ToString();
if (ret.Length > digits) return ret.Substring(0, digits);
else return ret + new String('0', digits - ret.Length);
}
Note that if your number has more than digits integer digits, this doesn't work...
What about something like:
d.ToString().PadRigth(4,'0').SubString(0,4);
public static void RunSnippet()
{
Console.WriteLine(myCustomFormatter(3.42421));
Console.WriteLine(myCustomFormatter(265.6250));
Console.WriteLine(myCustomFormatter(812.50));
Console.WriteLine(myCustomFormatter(12.68798));
Console.WriteLine(myCustomFormatter(0.68787));
Console.ReadLine();
}
public static double myCustomFormatter(double value)
{
string sValue = value.ToString();
string sFormattedValue = sValue.Substring(0,5);
double dFormattedValue= Convert.ToDouble(sFormattedValue);
return dFormattedValue;
}