Int.Parse（String.Split（））返回“输入字符串格式不正确”错误

Question

I am trying to perform a LINQ query on an array to filter out results based on a user's query. I am having a problem parsing two int 's from a single string.

In my database, TimeLevels are stored as strings in the format [mintime]-[maxtime] minutes for example 0-5 Minutes . My user's have a slider which they can select a min and max time range, and this is stored as an int array, with two values. I'm trying to compare the [mintime] with the first value, and the [maxtime] with the second, to find database entries which fit the user's time range.

Here is my C# code from the controller which is supposed to perform that filtering:

RefinedResults = InitialResults.Where(
                x => int.Parse(x.TimeLevel.Split('-')[0]) >= data.TimeRange[0] &&
                int.Parse(x.TimeLevel.Split('-')[1]) <= data.TimeRange[1] &&).ToArray();

My thinking was that it would firstly split the 0-5 Minutes string at the - resulting in two strings, 0 and 5 Minutes , then parse the ints from those, resulting in just 0 and 5 .

But as soon as it gets to Int.Parse, it throws the error in the title.

Answer 1

some of the x.TimeLevel database records are stored as "30-40+ Minutes" . Is there any method just to extract the int ?

You could use regular expressions to match the integer parts of the string for you, like this:

RefinedResults = InitialResults
    .Where(x => {
        var m = Regex.Match(x, @"^(\d+)-(\d+)");
        return m.Success
            && int.Parse(m.Groups[1]) >= data.TimeRange[0]
            && int.Parse(m.Groups[2]) <= data.TimeRange[1];
    }).ToArray();

This approach requires the string to start in a pair of dash-separated decimal numbers. It would ignore anything after the second number, ensuring that only sequences of digits are passed to int.Parse .

Answer 2

The reason your code doesn't work is because string.Split("-", "0-5 Minutes") will return [0] = "0" and [1] = "5 Minutes", and the latter is not parseable as an int.

You can use the regular expression "\\d+" to split up groups of digits and ignore non-digits. This should work:

var refinedResults = 
(
    from result in InitialResults
    let numbers = Regex.Matches(result.TimeLevel, @"\d+")
    where ((int.Parse(numbers[0].Value) >= data.TimeRange[0]) && (int.Parse(numbers[1].Value) <= data.TimeRange[1]))
    select result
).ToArray();

Here's a complete compilable console app which demonstrates it working. I've used dummy classes to represent your actual classes.

using System;
using System.Linq;
using System.Text.RegularExpressions;

namespace ConsoleApplication2
{
    public class SampleTime
    {
        public SampleTime(string timeLevel)
        {
            TimeLevel = timeLevel;
        }

        public readonly string TimeLevel;
    }

    public class Data
    {
        public int[] TimeRange = new int[2];
    }

    class Program
    {
        private static void Main(string[] args)
        {
            var initialResults = new []
            {
                new SampleTime("0-5 Minutes"),
                new SampleTime("4-5 Minutes"), // Should be selected below.
                new SampleTime("1-8 Minutes"),
                new SampleTime("4-6 Minutes"), // Should be selected below.
                new SampleTime("4-7 Minutes"),
                new SampleTime("5-6 Minutes"), // Should be selected below.
                new SampleTime("20-30 Minutes")
            };

            // Find all ranges between 4 and 6 inclusive.

            Data data = new Data();
            data.TimeRange[0] = 4;
            data.TimeRange[1] = 6;

            // The output of this should be (as commented in the array initialisation above):
            //
            // 4-5 Minutes
            // 4-6 Minutes
            // 5-6 Minutes

            // Here's the significant code:

            var refinedResults = 
            (
                from result in initialResults
                let numbers = Regex.Matches(result.TimeLevel, @"\d+")
                where ((int.Parse(numbers[0].Value) >= data.TimeRange[0]) && (int.Parse(numbers[1].Value) <= data.TimeRange[1]))
                select result
            ).ToArray();

            foreach (var result in refinedResults)
            {
                Console.WriteLine(result.TimeLevel);
            }
        }
    }
}

Answer 3

The problem is that you are splitting by - and not also by space which is the separator of the minutes part. So you could use Split(' ', '-') instead:

InitialResults
    .Where(x => int.Parse(x.TimeLevel.Split('-')[0]) >= data.TimeRange[0] 
             && int.Parse(x.TimeLevel.Split(' ','-')[1]) <= data.TimeRange[1])
    .ToArray();

As an aside, don't store three informations in one column in the database. That's just a source of nasty errors and bad performance. It's also more difficult to filter in the database which should be the preferred way or to maintain datatabase consistency.

---

Regarding your comment that the format can be 0-40+ Minutes . Then you could use...

InitialResults
    .Select(x => new { 
        TimeLevel = x.TimeLevel, 
        MinMaxPart = x.TimeLevel.Split(' ')[0]
    })
    .Select(x => new { 
        TimeLevel = x.TimeLevel, 
        Min = int.Parse(x.MinMaxPart.Split('-')[0].Trim('+')),
        Max = int.Parse(x.MinMaxPart.Split('-')[1].Trim('+'))
    })
    .Where(x => x.Min >= data.TimeRange[0] && x.Max <= data.TimeRange[1])
    .Select(x => x.TimeLevel)
    .ToArray();

Answer 4

Error happens because of the " Minutes" part of the string. You can truncate the " Minutes" part before splitting, like; x.TimeLevel.Remove(x.IndexOf(" ")) then you can split.