如何确定文本框中的字符串最长的行

Question

Trying to find the longest line by string in a textbox (multi-line). Longest will return the number of the line, for example:

line 1: good day, world
line 2: good evening world
line 3: good morning, world

the longest string found in textbox will return the number of the line which is line 3 something like MessageBox("MAX: 3") or show multiple lines if found same string.

Note: count " " space too.

so far i tried this way:

string[] stringArray = textBox1.Text.Split(' ');
var  Maximum = "";
var Minimum = textBox1.Lines[0];
foreach (string line in textBox1.Lines)
{
      int index = line.IndexOf(textBox1.Text);
      if (index > 0)
      { 
          if (Minimum.Length > line.Length)
          {
              Minimum = line;
          }

          if (Maximum.Length < line.Length)
          {
              Maximum = line;

           }
           MessageBox.Show(string.Format("MAX: {0} ", index));
       }

but for some reason it won't show it. Any idea why?

Answer 1

Your code splits the text of the textbox at spaces - you get "words". Then you foreach over all lines. Somehow you search the full text of your box inside of one line of the splitted text of your box. This can not work unless your textbox contains only 1 line without any newlines in it but then the whole thing does not make any sense anymore.

Use textBox1.Lines and check all lines for lenght, use the longest:

int i = 0;
int maxLen = -1;
int maxIndex = - 1;
foreach (var l in textBox1.Lines)
{
    if (l.Length > maxLen)
    {
        maxLen = l.Length;
        maxIndex = i;
    }
    i++;
}
// this will only capture the first line if multiple are same length
// maxLen holds the length of the longest line, maxIndex the index of it

---

If you want it fancier, use Linq:

You can use IEnumerable<T>.Select() for that - it has an overload that gives you the index as well. You create an anonymous type, OrderByDescending() it accordingly, get the Max() value from it and sort out Where() the length has this max value - you could shorten it without anonymous type but I think this way its clearer what happens:

using System;
using System.Linq;

public class Program
{
    public static void Main(string[] args)
    {
        string[] stringArray = new[] { // you get this array from Textbox.Lines
            "one line of text",
            "second line with more text",
            "short line",
            "very long line with text and more text",
            "very long line with text and more text" };

        var sorted = stringArray
            .Select((text, index) => new {Index=index, Text=text, Length=text.Length })
            .OrderByDescending(ano => ano.Length)
            .ToList(); // order by lenght descending
        var maxLength = sorted.Max(ano => ano.Length); // get max length

        var maxOnes = sorted.Where(ano => ano.Length == maxLength);

        foreach (var ano in sorted)
            Console.WriteLine(
                $"{ano.Index} has length {ano.Length} and text of '{ano.Text}'");

        Console.WriteLine(
            $"The longest ones had indexes: {string.Join(",",
                                             maxOnes.Select(ano => ano.Index))}");
        Console.ReadLine();
    }
}

Output:

3 has length 38 and text of 'very long line with text and more text'
4 has length 38 and text of 'very long line with text and more text'
1 has length 26 and text of 'second line with more text'
0 has length 16 and text of 'one line of text'
2 has length 10 and text of 'short line'
The longest ones had indexes: 3,4

Answer 2

Keeping things simple, this should do the job:

Int32 index = 0;
Int32 maxLength = 0;

String[] lines = textBox1.Lines;

for (Int32 i = 0; i < lines.Length; ++i)
{
    Int32 currLength = lines[i].Length;

    if (currLength > maxLength)
    {
        maxLength = currLength;
        index = i;
    }
}

MessageBox.Show(String.Format("MAX: {0}", index));

Alternatively, using LINQ and OrderByDescending together with IndexOf , you can proceed with the following code:

Int32 index = textBox1.Lines.IndexOf(textBox1.Lines.OrderByDescending(x => x.Length).First());
MessageBox.Show(String.Format("MAX: {0}", index));

Answer 3

Using LINQ will make this easy. Just order the lines by their length and use the last one because the longest will be at the end.

var lines = textBox1.Lines.ToList();
var longest = lines.OrderBy(line => line.Length).Last();
var index = lines.IndexOf(longest);

Answer 4

try Orderby and where:

        var stringOrdered = textBox1.Lines.OrderByDescending(t => t.Length);
        var mostLargeStrings = stringOrdered.Where(str=> str.Length == stringOrdered.First().Length);             
        var index = 0;
        foreach(var TXT in mostLargeStrings)
        {
            index = Array.IndexOf(textBox1.Lines, TXT, index+1);
            MessageBox.Show(string.Format("MAX: {0} ",index));
        }

the code, first order the text strings from the longest to the shortest and then take the ones with the same length as the first one, then we search for their index in textbox Lines