在一行最多 20 个字符的单词后拆分字符串

Question

I am trying to write a program which will split a user input of a very long sentence which every 20 characters, a new line is created. If the end of the 20 characters is in the middle of a word, it will print the previous full word

using System;

namespace stringToLines
{
    class Program
    {
        static void split()
        {
            string sent = Console.ReadLine();
            int a = sent.Length / 20;
            string[] line;

            int space = sent.IndexOf(' ');
            while (space < 20)
            {
                int i = 0;
                line[i] = sent.Substring(0, space);
                sent = sent.Substring(space, sent.Length-space);
                space = sent.IndexOf(' ');
                i++;
            }
            for (int i = 0; i <=a; i++)
            {
                Console.WriteLine(line[i],"\n");
            }
            Console.ReadLine();
            return split;
        }
        static void Main(string[] args)
        {
            Console.WriteLine("Please enter your long sentence(>20 characters)");

            split();
        }
    }
}

Answer 1

Your code includes a lot of errors. Some main errors are:

• You added a return value to a method without a return type
• You didn't initialize your string-array
• Your while loop will be infite, because after the first itteration your space parameter will always be 0

I would recommend you to read the Getting started documentation of .NET

To getting started with your current problem, you can take look at the following code. I added comments to explain whats happening:

using System;
using System.Collections.Generic;
using System.Text;

namespace stringToLines
{
    class Program
    {
        static void split()
        {
            string sent = Console.ReadLine(); //Read the input
            string[] split = sent.Split(' '); // Get the words of the input
            StringBuilder builder = new StringBuilder();
            int charCounter = 0;
            List<string> lines = new List<string>();
            foreach (string word in split) //Iterate through the words
            {
                charCounter += word.Length; //Add the word to the charCounter
                if (charCounter >= 20) { // Check if the charCounter exceeds the limi´t
                    lines.Add(builder.ToString().TrimEnd()); //Add the buffered line into the result list
                    builder.Clear(); // Clear the buffer
                    charCounter = word.Length; //Reset the char counter to the current length
                }
                builder.Append(word + " "); //Add the word plus a space to the buffer
            }

            lines.Add(builder.ToString().TrimEnd()); //Add Last Line

            foreach (string line in lines) //Iterate through the result list
                Console.WriteLine(line); // Print the result
            Console.ReadLine();
        }

        static void Main(string[] args)
        {
            Console.WriteLine("Please enter your long sentence(>20 characters)");

            split();
        }
    }
}

Answer 2

You don't ask a very clear question. I read that you want to break an entered text into lines that are a maximum of 20 characters long, but you don't want to break into a word itself. If that's your question, you can use the solution below:

Change your code:

static void Main(string[] args)
{
    Console.WriteLine("Please enter your long sentence(>20 characters)");

    var sent = Console.ReadLine();
    var lines = sent.SplitOnLastWhiteSpaceAt(20);

    for (int i = 0; i <= lines.Length; i++)
    {
        Console.WriteLine(lines[i], "\n");
    }

    Console.ReadLine("Press any key to close");
}

Use this string extension methode:

using System.Collections.Generic;

namespace stackoverflow.question_69882038.Extensions
{
    public static class StringExtensions
    {
        public static string[] SplitOnLastWhiteSpaceAt(this string value, int maxLength)
        {
            List<string> values = new List<string>();

            try
            {
                var _rest = value;

                while (_rest.Length > maxLength)
                {
                    for (var i = maxLength; i >= 0; i += -1)
                    {
                        //Start on end, Search last index of WhiteSpace
                        if (char.IsWhiteSpace(_rest[i]))
                        {
                            values.Add(_rest.Substring(0, i));
                            if (i > _rest.Length)
                                return values.ToArray();
                            //Last item is not Empty or WithSpace
                            _rest = _rest.Substring(i + 1);
                            //Remove the WithSpace where splitted on
                            break;
                            //No Whitespace was found. Split on maxLenght.
                        }
                        else if (i == 0)
                        {
                            values.Add(_rest.Substring(0, maxLength));
                            _rest = _rest.Substring(maxLength);
                            break;
                        }
                    }
                }

                if (_rest.Length > 1 || (_rest.Length > 0 && !char.IsWhiteSpace(_rest[0])))
                    values.Add(_rest);
                //Last item is not 1 Char as Empty or WithSpace

                return values.ToArray();
            }
            finally
            {
                values.Clear();
                value = null;
            }
        }
    }
}