C#: How to Check if a string is numeric in C# – 5 Best Method

Checking whether a string is numeric is a common task in C# programming, especially when dealing with user input, file parsing, or data validation. In this article, we’ll explore five different methods to check if a string is numeric in c#, along with their pros and cons.

Why check if a string is Numeric?

before processing user input (e.g., from forms, APIs, or files) you must ensure it’s a valid number to avoid runtime errors like FormatException. Common scenarios include:

• Validating user input in a textbox
• parsing CSV or JSON data
• Converting strings to integers, floats, or decimals

Method 1: Using int.TryParse() (For Integers)

The TrypParse() method is the simplest way to check if a string is numeric in c#. This method takes in a string and tries to parse it as an integer. If the string is a valid integer, then the method will return true and save the parsed integer value in the out parameter

string input = "125690";
bool isNumeric = int.TryParse(input, out int number);
Console.WriteLine(isNumeric);  // Output : True

Pros:

• Fast and efficient for integers
• Returns the parsed value if successful

Cons:

• Only works for integers (int), not floating-point numbers

Method 2: Using double.TryParse() (For Floating-Point Number)

if you need to check for decimal numbers, use double.TryParse().

string stringvalue = "9012.87";
bool isNumeric = int.TryParse(stringvalue , out double number);
Console.WriteLine(isNumeric);  // Output : True

Pros:

• Handles both integers and floating-point numbers
• Supports scientific notation (e.g., “1.23e4”)

Cons:

• incorrectly parse non-numeric strings with symbols (e.g, “$123” fails)

Method 3: Using decimal.TryParse() (For Financial/Precise Calculations)

if you need to check for financial applications, decimal.TryParse() is more precise.

string stringvalue = "901.876";
bool isNumeric = decimal.TryParse(stringvalue , out decimal number);
Console.WriteLine(isNumeric);  // Output : True

Pros:

• Better precision for financial calculations
• Avoids floating-point rounding errors

Cons:

• Slightly slower than double.TryParse()

Methos 4: Using Regex (For Custom Number Formats)

if you need strict control over number formats use regular expressions.

using System.Text.RegularExpressions;

string stringvalue = "-9012.87";
bool isNumeric = Regex.IsMatch(stringvalue, @"^-?\d+(\.\d+)?$");
Console.WriteLine(isNumeric);  // Output : True

Pros:

• Customizable for specific formats
• It works negative number

Cons:

• Slower than TryParse methods
• Complex regex can be hard to maintain

Methos 5: Using char.IsDigit() (For Simple Digit Checks)

if you only need to check if every character is a digit(no decimals or signs), use char.IsDigit().

string stringvalue = "901287";
bool isNumeric = strignvalue.All(char.IsDigit);
Console.WriteLine(isNumeric);  // Output : True

Pros:

• Simple for pure digit strings

Cons:

• It fails to support negative numbers or decimals

Performance Comparison

Method	Best For	Speed
int.TryParse()	integers	Fastest
double.Tryparse()	Floating-point numbers	Fast
decimal.TryParse()	Financial precision	Fast
Regex	custom formats	Slower
chr.IsDigit()	Pure digit only	Fast

More Reading:

• Microsoft Docs: int.TryParse