C# int.Parse Method

The int.Parse method in C# converts a string representation of a number to an integer. If the string cannot be converted to a valid integer, the method throws a FormatException.

Syntax

Following is the basic syntax for int.Parse −

int result = int.Parse(stringValue);

The method also has overloaded versions that accept additional parameters −

int result = int.Parse(stringValue, NumberStyles.Integer);
int result = int.Parse(stringValue, CultureInfo.InvariantCulture);

Parameters

• s − A string containing a number to convert.

• style (optional) − A bitwise combination of enumeration values that indicates the style elements.

• provider (optional) − An object that supplies culture-specific formatting information.

Return Value

Returns a 32-bit signed integer equivalent to the number contained in the string parameter.

Using int.Parse with Valid String

Example

using System;

class Program {
   static void Main() {
      string myStr = "200";
      int result = int.Parse(myStr);
      Console.WriteLine("String '" + myStr + "' converted to integer: " + result);
      
      string negativeStr = "-150";
      int negativeResult = int.Parse(negativeStr);
      Console.WriteLine("String '" + negativeStr + "' converted to integer: " + negativeResult);
   }
}

The output of the above code is −

String '200' converted to integer: 200
String '-150' converted to integer: -150

Exception Handling with int.Parse

When the string cannot be parsed as an integer, int.Parse throws a FormatException. It's good practice to handle this exception −

Example

using System;

class Program {
   static void Main() {
      string[] testStrings = {"123", "abc", "45.67", ""};
      
      foreach(string str in testStrings) {
         try {
            int result = int.Parse(str);
            Console.WriteLine("Successfully parsed '" + str + "' to: " + result);
         }
         catch(FormatException) {
            Console.WriteLine("Failed to parse '" + str + "' - invalid format");
         }
      }
   }
}

The output of the above code is −

Successfully parsed '123' to: 123
Failed to parse 'abc' - invalid format
Failed to parse '45.67' - invalid format
Failed to parse '' - invalid format

Using int.TryParse as Alternative

For safer parsing without exceptions, consider using int.TryParse which returns true if parsing succeeds −

Example

using System;

class Program {
   static void Main() {
      string[] values = {"100", "invalid", "250"};
      
      foreach(string value in values) {
         int result;
         bool success = int.TryParse(value, out result);
         
         if(success) {
            Console.WriteLine("Parsed '" + value + "' successfully: " + result);
         } else {
            Console.WriteLine("Could not parse '" + value + "'");
         }
      }
   }
}

The output of the above code is −

Parsed '100' successfully: 100
Could not parse 'invalid'
Parsed '250' successfully: 250

Comparison

Conclusion

The int.Parse method converts string representations of numbers to integers but throws exceptions for invalid input. For robust applications, consider using int.TryParse or proper exception handling to manage conversion failures gracefully.