C＃如何将数组中的字符串元素添加到字符串

Question

Need assistance to do this. Or advice about how to add string to string elements in array?

1. We have 2 txt files with 100 or more strings in each:

   domain.txt
   domain1
   domain2
   ..
   title.txt
   title1
   tilte2
   ..

2. and we have:

   string link = < ah ref="http://www.domain.com" target="_blank">title< /a>

3. After reading files we would have 2 string arrays - we need to replace domain.com with each string from domain.txt and title with each string from title.txt like this:

   < ah ref="http://www.domain1.com" target="_blank">title1< /a>
   < ah ref="http://www.domain2.com" target="_blank">title2< /a>
   ..

4. Save the result string array into 2 txt files in that way: from 1-50 strings to
   1.txt and from 50-100 to 2.txt file

What is the best way to do this by manipulating strings with strings array elements?

Answer 1

This is probably the simplest way to read the files:

    string[] domains = File.ReadAllLines("domain.txt");
    string[] titles = File.ReadAllLines("titles.txt");

To make the substitutions you can use string.Format :

    int n = domains.Length;
    string[] results = new string[n];

    for (int i = 0; i < n; ++i)
    {
        results[i] = string.Format(
            @"<a href=""http://{0}"" target=""_blank"">{1}</a>",
            domains[i], titles[i]);
    }

To write the output you can use Linq:

    File.WriteAllLines("file1.txt", results.Take(n / 2).ToArray());
    File.WriteAllLines("file2.txt", results.Skip(n / 2).ToArray());

If your template is a paramter you might want to construct the format string dynamically rather than hardcoding it. Here is an example of how you could do that:

using System;
using System.IO;
using System.Linq;

class Program
{
    static string escapeBraces(string s)
    {
        return s.Replace("{", "{{").Replace("}", "}}");
    }

    static string createFormatString(string template, params string[] parameters)
    {
        template = escapeBraces(template);

        for (int i =0; i < parameters.Length; ++i) {
            template = template.Replace(
                escapeBraces(parameters[i]),
                "{" + i + "}");
        }

        return template;
    }

    static void Main(string[] args)
    {
        string template = @"<a {}href=""http://www.domain.com"" target=""_blank"">title</a>";
        string formatString = createFormatString(template, "www.domain.com", "title");

        string[] domains = File.ReadAllLines("domain.txt");
        string[] titles = File.ReadAllLines("title.txt");

        int n = domains.Length;
        if (titles.Length != n)
            throw new InvalidDataException("There must be the same number domains and titles.");

        string[] results = new string[n];
        for (int i = 0; i < n; ++i)
        {
            results[i] = string.Format(formatString, domains[i], titles[i]);
        }

        File.WriteAllLines("file1.txt", results.Take(n / 2).ToArray());
        File.WriteAllLines("file2.txt", results.Skip(n / 2).ToArray());
    }
}

Answer 2

This is beautiful using LINQ and some nice methods from File :

string[] domains = File.ReadAllLines(@"C:/domains.txt");
string[] titles = File.ReadAllLines(@"C:/titles.txt");
if(domains.Length != titles.Length) { throw new InvalidOperationException(); }
string link = "<a href=\"http://www.{0}.com\" target=\"_blank\">{1}</a>";
var results = domains.Select((domain, i) => String.Format(link, domain, titles[i]));
File.WriteAllLines("results1.txt", results.Take(results.Length / 2).ToArray());
File.WriteAllLines("results2.txt", results.Skip(results.Length / 2).ToArray());

It isn't clear what you want if there are more than one-hundred domain/title pairs so I split them in half.

Answer 3

Another way is to do it lazily like this:

        static IEnumerable<string> ReadLinesLazily(string file)
    {
        using (var reader = new StreamReader(file))
        {
            string line = null;
            while ((line = reader.ReadLine()) != null)
            {
                yield return line;
            }
        }
    }

    static void Combine()
    {
        const string link = "<a href=\"{0}\">{1}</a>";
        var links = ReadLinesLazily("domains.txt").Zip(ReadLinesLazily("titels.txt"), (d, t) => String.Format(link, d, t))
        // write links here
    }