How can I check if a string is a number?

How can I check if a string is a number?

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I'd like to know on C# how to check if a string is a number (and just a number).

Example :

141241   Yes
232a23   No
12412a   No

and so on...

Is there a specific function?


Look up double.TryParse() if you're talking about numbers like 1, -2 and 3.14159. Some others are suggesting int.TryParse(), but that will fail on decimals.

double num;
string candidate = "1";
if (double.TryParse(candidate, out num))
{
    // It's a number!
}

EDIT: As Lukas points out below, we should be mindful of the thread culture when parsing numbers with a decimal separator, i.e. do this to be safe:

double.TryParse(candidate, NumberStyles.AllowDecimalPoint, CultureInfo.InvariantCulture, out num)

How to check if a String is numeric in Java, Java - How to check if a String is numeric. boolean isNumeric(final String str) { if (str == null || str.length() == 0) { return false; } try { Integer. Perhaps the easiest and the most reliable way to check whether a String is numeric or not is by parsing it using Java's built-in methods: Integer.parseInt(String) Float.parseFloat(String) Double.parseDouble(String) Long.parseLong(String) new BigInteger(String)


If you just want to check if a string is all digits (without being within a particular number range) you can use:

string test = "123";
bool allDigits = test.All(char.IsDigit);

Java - How to check if a String is numeric, Example 1: Check if a string is numeric To check if string contains numbers only, in the try block, we use Double 's parseDouble() method to convert the string to a Double . If it throws an error (i.e. NumberFormatException error), it means string isn't a number and numeric is set to false . Else, it's a number. If you just want to check if a string is all digits (without being within a particular number range) you can use: string test = "123"; bool allDigits = test.All(char.IsDigit);


Yes there is

int temp;
int.TryParse("141241", out temp) = true
int.TryParse("232a23", out temp) = false
int.TryParse("12412a", out temp) = false

Hope this helps.

Java Program to Check if a String is Numeric, Integer class provides a static method parseInt() which will throw NumberFormatException if the String does not contain a parsable int. We will catch this exception� 1. # -*- coding: utf-8 -*-. The following function is arguably one of the quickest and easiest methods to check if a string is a number. It supports str, and Unicode, and will work in Python 3 and Python 2.


Use Int32.TryParse()

int num;

bool isNum = Int32.TryParse("[string to test]", out num);

if (isNum)
{
    //Is a Number
}
else
{
    //Not a number
}

MSDN Reference

Check if a given string is a valid number (Integer or Floating Point) in , CPP program to check if a given string. // is a valid integer. #include <iostream>. using namespace std;. // Returns true if s is a number else false. The question didn't explicitly specify it, but my understanding of the requirement "checks if a string is a number" means that the whole string is the number, thus no spaces. I felt the need to point out that your answer is different to the others in this regard.


Use int.TryParse():

string input = "141241";
int ouput;
bool result = int.TryParse(input, out output);

result will be true if it was.

Program to check if input is an integer or a string, The most efficient way would be just to iterate over the string until you find a non-digit character. If there are any non-digit characters, you can consider the string not a number.


Using Apache Commons StringUtils.isNumeric() to verify if String is valid number. Here are a couple of examples for different input to check if String is a valid number or not, this will give you a good idea of how this method works and what you can expect from this method.


To check if string contains numbers only, in the try block, we use Double 's parseDouble () method to convert the string to a Double. If it throws an error (i.e. NumberFormatException error), it means string isn't a number and numeric is set to false. Else, it's a number.