How to Convert String to Int in C# (Developer Tutorial)

Using int.Parse()

The int.Parse() method is a straightforward way to convert a string to an integer. However, it assumes that the input string is in the correct format (i.e., a valid number) and will throw a FormatException if the conversion fails.

int number = int.Parse("123");

int number = int.Parse("123");

Advantages:

• Simple and direct for valid string inputs.

Disadvantages:

• Throws an exception if the string is not a valid number, which may not be ideal when processing untrusted data (such as user input or data from external files).

Using int.TryParse()

For safer conversions, the TryParse method is commonly used. It attempts the conversion and returns a boolean value indicating whether the conversion was successful or not. If the conversion fails, it does not throw an exception but simply returns false. The result is stored in an out parameter.

bool success = int.TryParse("123", out int result);

bool success = int.TryParse("123", out int result);

Here, success is a boolean value indicating whether the conversion succeeded, and result is the converted integer, stored in the out parameter.

Advantages:

• Handles invalid strings gracefully by returning false instead of throwing exceptions.
• Ideal for scenarios where you are unsure if the string is a valid number.

Disadvantages:

• Requires an additional check (the boolean result) to confirm whether the conversion succeeded.

Using the Convert Class

Another way to convert a string variable into an integer value is to use the Convert class. The convert class includes methods that can convert different data types, including strings to integers.

int number = Convert.ToInt32("123");

int number = Convert.ToInt32("123");

Advantages:

• The Convert class can handle a wider range of data types beyond just strings and integers.

Disadvantages:

• Like the parse method, if the string variable is not in the correct format, this method throws a FormatException.

IronPDF Features

IronPDF offers a comprehensive set of features for working with PDFs, including:

• PDF Conversion: IronPDF can convert HTML to PDF, with its full support for modern web standards. You can be assured that IronPDF will consistently return pixel-perfect PDFs from your HTML page or content. IronPDF can also convert PDF files from other formats such as DOCX, images, RTF, and more.
• PDF Generation: With IronPDF, you can generate PDFs from URLs, ASPX files, or HTML strings.
• Security Features: With IronPDF, you can always be assured that any sensitive PDF files are secure thanks to its security features. Use IronPDF to encrypt your PDF files, set passwords, and set permissions for your PDF files.
• PDF Editing Features: With IronPDF you can process existing PDF documents, edit them, and read PDF files with ease. IronPDF offers editing features such as adding headers and footers, stamping text and images onto the PDF pages, adding custom watermarks to the PDF, working with PDF forms, and splitting or merging PDF files.
• Integration: Seamlessly integrates with ASP.NET and MVC applications.
• PDF Version Support: Support for PDF versions 1.2-1.7.

These features make IronPDF a powerful tool for any application that requires PDF functionality, from simple reports to complex document processing systems.

Example Code for Extracting Numbers from PDF Text

Using IronPDF, you can extract text from a PDF and then convert any numerical strings into integers using int.TryParse(). Here’s how:

using System;
using System.Text.RegularExpressions;
using IronPdf;

public static class PdfNumberExtractor
{
    public static void Main(string[] args)
    {
        // Load the PDF file
        PdfDocument pdf = PdfDocument.FromFile("invoice.pdf");

        // Extract text from the PDF
        string extractedText = pdf.ExtractAllText();

        // Use regex to extract potential numbers from the text
        var matches = Regex.Matches(extractedText, @"\d+");

        if (matches.Count > 0)
        {
            Console.WriteLine("Extracted number(s) from PDF:");

            foreach (Match match in matches)
            {
                // Try to parse each match as an integer
                if (int.TryParse(match.Value, out int num))
                {
                    Console.WriteLine(num); // If successful, print the number
                }
            }
        }
        else
        {
            Console.WriteLine("Could not find any numbers in the extracted text.");
        }
    }
}

using System;
using System.Text.RegularExpressions;
using IronPdf;

public static class PdfNumberExtractor
{
    public static void Main(string[] args)
    {
        // Load the PDF file
        PdfDocument pdf = PdfDocument.FromFile("invoice.pdf");

        // Extract text from the PDF
        string extractedText = pdf.ExtractAllText();

        // Use regex to extract potential numbers from the text
        var matches = Regex.Matches(extractedText, @"\d+");

        if (matches.Count > 0)
        {
            Console.WriteLine("Extracted number(s) from PDF:");

            foreach (Match match in matches)
            {
                // Try to parse each match as an integer
                if (int.TryParse(match.Value, out int num))
                {
                    Console.WriteLine(num); // If successful, print the number
                }
            }
        }
        else
        {
            Console.WriteLine("Could not find any numbers in the extracted text.");
        }
    }
}

Input PDF

Console Output

In this code example, we start by loading the PDF file named "invoice.pdf" and before extracting all of the text from the document using the ExtractAllText() method. To identify potential numbers within the extracted text, the code applies a regular expression (regex) \d+, which matches sequences of digits.

The matches are stored, and if any numbers are found, they are displayed on the console. Each match is individually parsed as an integer using int.TryParse(), ensuring only valid numeric values are processed. If no numbers are found, a message is displayed stating that no numbers were extracted. This approach is useful for processing PDFs containing numeric data, such as invoices, where extracting and converting numbers is essential.