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Convert IsNumeric(textbox.Text) vb net code in c# [duplicate]

I know it's possible to check whether the value of a text box or variable is numeric using try/catch statements, but IsNumeric is so much simpler. One of my current projects requires recovering values from text boxes. Unfortunately, it is written in C#.
I understand that there's a way to enable the Visual Basic IsNumeric function in Visual C# by adding a reference to Visual Basic, though I don't know the syntax for it. What I need is a clear and concise walkthrough for enabling the IsNumeric function in C#. I don't plan on using any other functions indigenous to Visual Basic.

public bool IsNumeric(string value)
{
return value.All(char.IsNumber);
}

To totally steal from Bill answer you can make an extension method and use some syntactic sugar to help you out.
Create a class file, StringExtensions.cs
Content:
public static class StringExt
{
public static bool IsNumeric(this string text)
{
double test;
return double.TryParse(text, out test);
}
}
EDIT: This is for updated C# 7 syntax. Declaring out parameter in-line.
public static class StringExt
{
public static bool IsNumeric(this string text) => double.TryParse(text, out _);
}
Call method like such:
var text = "I am not a number";
text.IsNumeric() //<--- returns false

You could make a helper method. Something like:
public bool IsNumeric(string input) {
int test;
return int.TryParse(input, out test);
}

It is worth mentioning that one can check the characters in the string against Unicode categories - numbers, uppercase, lowercase, currencies and more. Here are two examples checking for numbers in a string using Linq:
var containsNumbers = s.Any(Char.IsNumber);
var isNumber = s.All(Char.IsNumber);
For clarity, the syntax above is a shorter version of:
var containsNumbers = s.Any(c=>Char.IsNumber(c));
var isNumber = s.All(c=>Char.IsNumber(c));
Link to unicode categories on MSDN:
UnicodeCategory Enumeration

Using C# 7 (.NET Framework 4.6.2) you can write an IsNumeric function as a one-liner:
public bool IsNumeric(string val) => int.TryParse(val, out int result);
Note that the function above will only work for integers (Int32). But you can implement corresponding functions for other numeric data types, like long, double, etc.

http://msdn.microsoft.com/en-us/library/wkze6zky.aspx
menu:
Project-->Add Reference
click: assemblies, framework
Put a checkmark on Microsoft.VisualBasic.
Hit OK.
That link is for Visual Studio 2013, you can use the "Other versions" dropdown for different versions of visual studio.
In all cases you need to add a reference to the .NET assembly "Microsoft.VisualBasic".
At the top of your c# file you neeed:
using Microsoft.VisualBasic;
Then you can look at writing the code.
The code would be something like:
private void btnOK_Click(object sender, EventArgs e)
{
if ( Information.IsNumeric(startingbudget) )
{
MessageBox.Show("This is a number.");
}
}

Try following code snippet.
double myVal = 0;
String myVar = "Not Numeric Type";
if (Double.TryParse(myVar , out myNum)) {
// it is a number
} else {
// it is not a number
}

I usually handle things like this with an extension method. Here is one way implemented in a console app:
namespace ConsoleApplication10
{
class Program
{
static void Main(string[] args)
{
CheckIfNumeric("A");
CheckIfNumeric("22");
CheckIfNumeric("Potato");
CheckIfNumeric("Q");
CheckIfNumeric("A&^*^");
Console.ReadLine();
}
private static void CheckIfNumeric(string input)
{
if (input.IsNumeric())
{
Console.WriteLine(input + " is numeric.");
}
else
{
Console.WriteLine(input + " is NOT numeric.");
}
}
}
public static class StringExtensions
{
public static bool IsNumeric(this string input)
{
return Regex.IsMatch(input, #"^\d+$");
}
}
}
Output:
A is NOT numeric.
22 is numeric.
Potato is NOT numeric.
Q is NOT numeric.
A&^*^ is NOT numeric.
Note, here are a few other ways to check for numbers using RegEx.

Tested with Net6 and universal with object because needed in my app:
public static bool IsNumeric(this object text) => double.TryParse(Convert.ToString(text), out _);
Works with null and string.empty and also tested "".

Is numeric can be achieved via many ways, but i use my way
public bool IsNumeric(string value)
{
bool isNumeric = true;
char[] digits = "0123456789".ToCharArray();
char[] letters = value.ToCharArray();
for (int k = 0; k < letters.Length; k++)
{
for (int i = 0; i < digits.Length; i++)
{
if (letters[k] != digits[i])
{
isNumeric = false;
break;
}
}
}
return isNumeric;
}

In C#, how to check whether a string contains an integer?

I just want to know, whether a String variable contains a parsable positive integer value. I do NOT want to parse the value right now.
Currently I am doing:
int parsedId;
if (
(String.IsNullOrEmpty(myStringVariable) ||
(!uint.TryParse(myStringVariable, out parsedId))
)
{//..show error message}
This is ugly - How to be more concise?
Note: I know about extension methods, but I wonder if there is something built-in.

You could use char.IsDigit:
bool isIntString = "your string".All(char.IsDigit)
Will return true if the string is a number
bool containsInt = "your string".Any(char.IsDigit)
Will return true if the string contains a digit

Assuming you want to check that all characters in the string are digits, you could use the Enumerable.All Extension Method with the Char.IsDigit Method as follows:
bool allCharactersInStringAreDigits = myStringVariable.All(char.IsDigit);

Maybe this can help
string input = "hello123world";
bool isDigitPresent = input.Any(c => char.IsDigit(c));
answer from msdn.

You can check if string contains numbers only:
Regex.IsMatch(myStringVariable, #"^-?\d+$")
But number can be bigger than Int32.MaxValue or less than Int32.MinValue - you should keep that in mind.
Another option - create extension method and move ugly code there:
public static bool IsInteger(this string s)
{
if (String.IsNullOrEmpty(s))
return false;
int i;
return Int32.TryParse(s, out i);
}
That will make your code more clean:
if (myStringVariable.IsInteger())
// ...

This work for me.
("your string goes here").All(char.IsDigit)

Sorry, didn't quite get your question. So something like this?
str.ToCharArray().Any(char.IsDigit);
Or does the value have to be an integer completely, without any additional strings?
if(str.ToCharArray().All(char.IsDigit(c));

string text = Console.ReadLine();
bool isNumber = false;
for (int i = 0; i < text.Length; i++)
{
if (char.IsDigit(text[i]))
{
isNumber = true;
break;
}
}
if (isNumber)
{
Console.WriteLine("Text contains number.");
}
else
{
Console.WriteLine("Text doesn't contain number.");
}
Console.ReadKey();
Or Linq:
string text = Console.ReadLine();
bool isNumberOccurance =text.Any(letter => char.IsDigit(letter));
Console.WriteLine("{0}",isDigitPresent ? "Text contains number." : "Text doesn't contain number.");
Console.ReadKey();

The answer seems to be just no.
Although there are many good other answers, they either just hide the uglyness (which I did not ask for) or introduce new problems (edge cases).

check for valid number input - console application

I have a little problem with a simple console application in which i would like to detect if the user inputs a correctly formatted numerical value.
That is, values such as 1212sss or anything like asjkq12323 or a single character is not accepted. I would like to only accept pure integer values.
Here is what i have tried
bool detectNumber(string s)
{
int value=0;
Int.TryParse(s,out value);
return (value!=0)?true:false;
}
I appreciate any help. Thank you soooo much,,,,,

TryParse returns a boolean. Check that, not the value passed via the out parameter.
if( int.TryParse( s, out value ) )
{
// do something
}
Or just:
return int.TryParse( s, out value );
Incidentally, it is not necessary to initialize a value passed using the out keyword. The method declaring the parameter must initialize it before returning.
int foo; // legal
int.TryParse( "123", out foo );
All BCL "Try" methods follow the same convention (such as double.TryParse() for floating point numbers, as #gdoron mentioned in the comments).
And for the curious, source code for the underlying library which implements int.TryParse().

int value = 0;
bool ok = int.TryParse(s, out value);
return ok;

string line = Console.ReadLine();
int value;
if (int.TryParse(line, out value))
{
Console.WriteLine("Integer here!");
}
else
{
Console.WriteLine("Not an integer!");
}

There are several ways to test for only numeric numbers:
first of all, never use Int because of it's maximum value, either use int or Int32.
Parse
int result;
if (int.TryParse("123", out result))
{
Debug.WriteLine("Valid integer: " + result);
}
else
{
Debug.WriteLine("Not a valid integer");
}
Convert.ToInt32()
// throws ArgumentNullExceptionint
result1 = Int32.Parse(null);
// doesn't throw an exception, returns 0
int result2 = Convert.ToInt32(null);
IsNumeric()
using Microsoft.VisualBasic;
// ......
bool result = Information.IsNumeric("123");
Pattern Matching
string strToTest = "123";
Regex reNum = new Regex(#"^\d+$");
bool isNumeric = reNum.Match(strToTest).Success;

Your code works normal, you can only refactor it a bit. Following code is shorter but does exactly the same:
static bool IsInt32(string s)
{
int value;
return Int32.TryParse(s, out value);
}

c# code to check whether a string is numeric or not

I am using Visual Studio 2010.I want to check whether a string is numeric or not.Is there any built in function to check this or do we need to write a custom code?

You could use the int.TryParse method. Example:
string s = ...
int result;
if (int.TryParse(s, out result))
{
// The string was a valid integer => use result here
}
else
{
// invalid integer
}
There are also the float.TryParse, double.TryParse and decimal.TryParse methods for other numeric types than integers.
But if this is for validation purposes you might also consider using the built-in Validation controls in ASP.NET. Here's an example.

You can do like...
string s = "sdf34";
Int32 a;
if (Int32.TryParse(s, out a))
{
// Value is numberic
}
else
{
//Not a valid number
}

You can use Int32.TryParse()
http://msdn.microsoft.com/en-us/library/f02979c7.aspx

Yes there is: int.TryParse(...) check the out bool param.

Have a look at this question:
What is the C# equivalent of NaN or IsNumeric?

You can use built in methods Int.Parse or Double.Parse methods. You can write the following function and call where ever necessary to check it.
public static bool IsNumber(String str)
{
try
{
Double.Parse(str);
return true;
}
catch (Exception)
{
return false;
}
}

The problem with all the Double/Int32/... TryParse(...) methods is that with a long enough numeric string, the method will return false;
For example:
var isValidNumber = int.TryParse("9999999999", out result);
Here, isValidNumber is false and result is 0, although the given string is numeric.
If you don't need to use the string as int, I would go with regular expressions validation on this one:
var isValidNumber = Regex.IsMatch(input, #"^\d+$")
This will only match integers. "123.45" for example, will fail.
If you need to check for floating point numbers:
var isValidNumber = Regex.IsMatch(input, #"^[0-9]+(\.[0-9]+)?$")
Note: try to create a single Regex object and send it to your int testing method for better performance.

Try this:
string Str = textBox1.Text.Trim();
double Num;
bool isNum = double.TryParse(Str, out Num);
if (isNum)
MessageBox.Show(Num.ToString());
else
`enter code here`MessageBox.Show("Invalid number");

Use IsNumeric() to check whether given string is numeric or not. It always return True for numeric value regardless whether it is Int or Double.
string val=...;
bool b1 = Microsoft.VisualBasic.Information.IsNumeric(val);

using System;
namespace ConsoleApplication1
{
class Test
{
public static void Main(String[] args)
{
bool check;
string testStr = "ABC";
string testNum = "123";
check = CheckNumeric(testStr);
Console.WriteLine(check);
check = CheckNumeric(testNum);
Console.WriteLine(check);
Console.ReadKey();
}
public static bool CheckNumeric(string input)
{
int outPut;
if (int.TryParse(input, out outPut))
return true;
else
return false;
}
}
}
This will work for you!!

Try This-->
String[] values = { "87878787878", "676767676767", "8786676767", "77878785565", "987867565659899698" };
if (Array.TrueForAll(values, value =>
{
Int64 s;
return Int64.TryParse(value, out s);
}
))
Console.WriteLine("All elements are integer.");
else
Console.WriteLine("Not all elements are integer.");

Check string for only digits and one optional decimal point.

I need to check if a string contains only digits. How could I achieve this in C#?
string s = "123" → valid
string s = "123.67" → valid
string s = "123F" → invalid
Is there any function like IsNumeric?

double n;
if (Double.TryParse("128337.812738", out n)) {
// ok
}
works assuming the number doesn't overflow a double
for a huge string, try the regexp:
if (Regex.Match(str, #"^[0-9]+(\.[0-9]+)?$")) {
// ok
}
add in scientific notation (e/E) or +/- signs if needed...

Taken from MSDN (How to implement Visual Basic .NET IsNumeric functionality by using Visual C#):
// IsNumeric Function
static bool IsNumeric(object Expression)
{
// Variable to collect the Return value of the TryParse method.
bool isNum;
// Define variable to collect out parameter of the TryParse method. If the conversion fails, the out parameter is zero.
double retNum;
// The TryParse method converts a string in a specified style and culture-specific format to its double-precision floating point number equivalent.
// The TryParse method does not generate an exception if the conversion fails. If the conversion passes, True is returned. If it does not, False is returned.
isNum = Double.TryParse(Convert.ToString(Expression), System.Globalization.NumberStyles.Any, System.Globalization.NumberFormatInfo.InvariantInfo, out retNum );
return isNum;
}

You can use double.TryParse
string value;
double number;
if (Double.TryParse(value, out number))
Console.WriteLine("valid");
else
Console.WriteLine("invalid");

This should work no matter how long the string is:
string s = "12345";
bool iAllNumbers = s.ToCharArray ().All (ch => Char.IsDigit (ch) || ch == '.');

Using regular expressions is the easiest way (but not the quickest):
bool isNumeric = Regex.IsMatch(s,#"^(\+|-)?\d+(\.\d+)?$");

As stated above you can use double.tryParse
If you don't like that (for some reason), you can write your own extension method:
public static class ExtensionMethods
{
public static bool isNumeric (this string str)
{
for (int i = 0; i < str.Length; i++ )
{
if ((str[i] == '.') || (str[i] == ',')) continue; //Decide what is valid, decimal point or decimal coma
if ((str[i] < '0') || (str[i] > '9')) return false;
}
return true;
}
}
Usage:
string mystring = "123456abcd123";
if (mystring.isNumeric()) MessageBox.Show("The input string is a number.");
else MessageBox.Show("The input string is not a number.");
Input :
123456abcd123
123.6
Output:
false
true

I think you can use Regular Expressions, in the Regex class
Regex.IsMatch( yourStr, "\d" )
or something like that off the top of my head.
Or you could use the Parse method int.Parse( ... )

If you are receiving the string as a parameter the more flexible way would be to use regex as described in the other posts.
If you get the input from the user, you can just hook on the KeyDown event and ignore all keys that are not numbers. This way you'll be sure that you have only digits.

This should work:
bool isNum = Integer.TryParse(Str, out Num);