I am trying to convert a string that has additional ASCII, e.g.:
string text = "123abc";
to an integer. What I want to do is extract the 123 from the above and put it into an integer without generating an exception.
I've tried using:
Int32.TryParse(text, out int intValue);
intValue is always 0.
You can use Regex to find the numeric values from string.
Regex.Match(text, @"\d+").Value;
Below is the working example.
You can filter out every character in the string that's not a number and then use int.Parse to parse the resulting string, using LINQ something like. Using int.Parse instead of int.TryParse should be ok as we filtered everything that's not a digit. It may still fail though if the filtered string of numbers exceeds the bounds of an integer.
string original = "123abc";
IEnumerable<char> filtered = original.Where(x => Char.IsDigit(x));
string filteredString = new string(filtered.ToArray());
int number = int.Parse(filteredString);
Or in one line (and using some syntax sugar):
var number = int.Parse(original.Where(Char.IsDigit).ToArray());
This assumes you want the string 12a3 to parse to the number 123, if you want it to only parse the first number found, use Kiran Joshi's answer. If you want it to parse to multiple numbers, you can also use Kiran's answer and iterate over the match groups from the regex.
total = total * 10 + parsed digit, but code is read more than written so I prefered readability hereAssuming you want the first part as an integer. "123abc12" --> 123
internal class Program
{
static void Main(string[] args)
{
string str = "123abc12";
int number = Convert(str);
Console.WriteLine(number);
}
public static int Convert(string str)
{
var span = str.AsSpan();
var length = span.Length;
for (int i = 0; i < span.Length; i++)
{
if (!char.IsDigit(span[i]))
{
length = i;
break;
}
}
if (int.TryParse(span[..length], out int number))
{
return number;
}
return 0;
}
}
If you want "123abc12" --> 12312
public static int Convert(string str)
{
Span<char> span = stackalloc char[10];
var j = 0;
for (int i = 0; i < str.Length && j < 10; i++)
{
if (char.IsDigit(str[i]))
{
span[j++] = str[i];
}
}
if (int.TryParse(span[..j], out int number))
{
return number;
}
return 0;
}
Method 1: Using Regular Expressions
using System; using System.Text.RegularExpressions;
public class Program
{
public static void Main()
{
string text = "123abc";
string numberString = Regex.Match(text, @"\d+").Value; // Extracts continuous digits
int number = int.Parse(numberString); // Converts the string to an integer
Console.WriteLine(number);
}
}
Method 2: Manual Iteration
using System;
public class Program
{
public static void Main()
{
string text = "123abc";
string numberString = "";
foreach (char c in text)
{
if (char.IsDigit(c))
{
numberString += c;
}
}
int number = int.Parse(numberString); // Converts the collected digits into an integer
Console.WriteLine(number);
}
}
Regular Expressions: This method uses the Regex class to identify and extract digits from the string efficiently. It's ideal for handling complex patterns quickly but might be less intuitive if you're not familiar with regex syntax.
Manual Iteration: This method involves checking each character to see if it's a digit and then forming the integer manually. It offers more control and is straightforward, making it easier to understand if you're new to regular expressions.
Both methods will correctly convert the string "123abc" to the integer 123. Choose based on your preference for simplicity or flexibility.
If you want to get separate numbers, I would do this:
string str = "123abc456def";
List<int> nums = new();
string num = string.Empty;
foreach (var c in str.ToCharArray())
{
if (Char.IsDigit(c))
num += c;
else
{
if (!num.IsNullOrEmpty())
nums.Add(int.Parse(num));
num = string.Empty;
}
}
12ab3c? Would you want12or3or123?