C# program to count how many strings have the same first and last chars as these in a list

Question

I need to write a program to count the number of strings where the string length is 2 or more and the first and last character are same as these in certain list with strings ["people", "desk", "orange", "yellow", "carrot", "pineapple"]

example: Input: "pe" , result- 2 -same as “people” и “pineapple ”

For now I did this, it search if the first and last chars are the same:

        List<string> stringsList = new List<string> { "people", "desk", "orange", "yellow", "carrot", "pineapple"};

        int count = 0;

        foreach (var c in stringsList)
        {
            if (c.Length > 1 && c[0] == c[-1])
            {
                count += 1;
            }
        }
        Console.WriteLine(count);

Answer 1

You can use linq for this purpose. So you need to

• filter by length
• compare the first letter with input
• compare the final letter with input

So code looks like this:

List<string> stringsList = new List<string> { "people", "desk", "orange", 
    "yellow", "carrot", "pineapple" };

int count = 0;
var input = "pe";
count = stringsList.Where(s => s.Length > 2 
            &&  s[0] == input[0] 
            && s[s.Length - 1] == input[1])
            .Count();

Answer 2

Try the answer below:

   //I'll let you input however you want to. Probably use console.ReadLine();
    string input = Console.ReadLine();
    int count;
    List<string> stringsList = new List<string> { "people", "desk", "orange", "yellow", "carrot", "pineapple"};

            foreach (string item in stringsList)
            {
                if (input.Length > 1 && item.Length > 1)
                {
                    if(input[input.Length - 1] == item[item.Length - 1])
                    {
                        //Same Last character
                        if(input[0] == item[0])
                        {
                            //Same first character
                            count += 1;
                        }
                    }
                }
            }
            Console.WriteLine(count);

Answer 3

You can query with a help of Linq :

using System.Linq;

...

List<string> stringsList = new List<string> { 
  "people", "desk", "orange", "yellow", "carrot", "pineapple"
};

string input = "pe";

int count = stringsList
  .Count(word => word.Length >= 2 && 
                 word[0] == input[0] && 
                 word[word.Length - 1] == input[input.Length - 1]);

Or even

int count = stringsList
  .Count(word => word.Length >= 2 && 
                 word.First() == input.First() && 
                 word.Last() == input.Last());

Answer 4

If you are using C#8 and .Net Core 3, you can use the new "index from end" operator to get at the last character of a string, to simplify the code somewhat.

For example, the last character of a string str is given by str[^1] .

So you could use the Linq Count() operator to count all the strings of length >=2 where the first and last characters match the target; for example:

using System;
using System.Collections.Generic;
using System.Linq;

namespace CoreConsole
{
    public static class Program
    {
        static void Main()
        {
            List<string> stringsList = new List<string> { "people", "desk", "orange", "yellow", "carrot", "pineapple" };

            string search = "pe";

            int n = stringsList.Count(str => 
                str.Length >= 2
                && str[ 0] == search[0] 
                && str[^1] == search[1]);

            Console.WriteLine(n);
        }
    }
}

Answer 5

Thanks, this is what I did:

        foreach (var c in stringsList)
        {
            if (c.Length > 1 && c[0] == input[0] && c[c.Length-1] == input[1])
            {
                count += 1;
            }
        }