how to read a text file and display some lines from it in C# ?

Question

masterinex 0 Newbie Poster

14 Years Ago

Hello,

I am trying to write a simple program which should read the first line from the file s1,
and display it. When I run it , I get the message

cannot implicitly convert 'System.IO.Streamreader 'to 's1.Program'
which happens for the line Program re = new StreamReader("s1.txt");

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace s1
{
    class Program
    {
        static void Main(string[] args)

        {
            Program re = new StreamReader("s1.txt");

            s = re.Readline();

            System.Console.WriteLine(s);
            System.Console.WriteLine("Hello, World!");


        }
    }
}

.net:c#

Edited 14 Years Ago by kvprajapati because: added [code] tags.

4 Contributors
20 Replies
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8 Hours Discussion Span
Latest Post 14 Years Ago Latest Post by Momerath

Dani AI

Generated 9 Months Ago

Brief summary and fixes (for ): the compile error came from assigning a StreamReader to a variable declared as your Program class — they are different types. already pointed that out. The runtime output of "System.String[]" happened because you passed a string[] to Console.WriteLine, and that prints the array’s type name, not its contents.

A few practical points you can apply right away:

To print the whole file, join the lines: use string.Join(Environment.NewLine, ...) or enumerate the array.
Indexing a string like someLine[0] returns a char (the first character). To get the first word, split the line; to get the last word, take the last element of the split result.
Use a split that ignores extra spaces/tabs to avoid empty entries: supply a char[] and StringSplitOptions.RemoveEmptyEntries.

A minimal, robust pattern (avoids loading the entire file and handles blank lines):

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

class Example
{
    static void Main()
    {
        var path = "s1.txt";
        var firstLine = File.ReadLines(path).FirstOrDefault();
        if (firstLine == null) return;
        var words = firstLine.Split(new[] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries);
        var firstWord = words.Length > 0 ? words[0] : "(none)";
        var lastWord  = words.Length > 0 ? words[words.Length - 1] : "(none)";
        Console.WriteLine(firstWord);
        Console.WriteLine(lastWord);
    }
}

Troubleshooting tips: check the file path and file existence, Trim() words to remove punctuation if needed, and guard against empty files or lines to avoid IndexOutOfRange. ’s StreamReader approach is fine for small samples; for large files prefer File.ReadLines or a using StreamReader to avoid leaking resources.

All 20 Replies

Momerath 1,327 Nearly a Senior Poster

14 Years Ago

String.Split returns an array, not a single string

foreach (String line in lines) {
    String[] parts = line.Split(' ');
    Console.WriteLine(parts[0]); // first part
}

Momerath 1,327 Nearly a Senior Poster

14 Years Ago

String.Split returns an array, not a single string

foreach (String line in lines) {
    String[] parts = line.Split(' ');
    Console.WriteLine(parts[0]); // first part
}

Momerath 1,327 Nearly a Senior Poster

14 Years Ago

String.Split returns an array, not a single string

foreach (String line in lines) {
    String[] parts = line.Split(' ');
    Console.WriteLine(parts[0]); // first part
}

Momerath 1,327 Nearly a Senior Poster

14 Years Ago

String.Split returns an array, not a single string

foreach (String line in lines) {
    String[] parts = line.Split(' ');
    Console.WriteLine(parts[0]); // first part
}

Momerath 1,327 Nearly a Senior Poster

14 Years Ago

String.Split returns an array, not a single string

foreach (String line in lines) {
    String[] parts = line.Split(' ');
    Console.WriteLine(parts[0]); // first part
}

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Momerath 1,327 Nearly a Senior Poster Featured Poster · Answer 1 · 2012-03-27T17:43:40+00:00

Program is a class, StreamReader is a constructor that constructs a class of type StreamReader. The Program class is not a StreamReader class.
After you figure that out, you'll get an error in line 4 :)

thines01 401 Postaholic Team Colleague Featured Poster · Answer 2 · 2012-03-27T17:58:47+00:00

One great benefit of this site is the great number of questions that have already been answered that you can search through.
If you were to use the word StreamReader in the search window, you would probably get a multitude of examples.

Mitja Bonca 557 Nearly a Posting Maven · Answer 3 · 2012-03-27T18:28:35+00:00

Hmm, here is much work to be done.
You are really messing things.
This code does not even complie.

To do your simple program, you can do:

class Program
{
    static void Main(string[] args)
    {
        string filePath = @"C:\YourFolder\testFile.txt";
        StreamReader sr = new Streamreader(filePath);
        string line = "";
        for (int i = 0; i < 1; i++)
            line = sr.ReadLine();
        sr.Dispose();
        Console.WriteLine(line);
        Console.ReadLine();            
    }
}

masterinex 0 Newbie Poster · Answer 4 · 2012-03-27T22:54:24+00:00

thank you for all the suggesions.

I made the change but, C# still got the error.
to go around it I have changed the code abit.
Now I am getting System.String[] when i run it.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace s1
{
    class Program
    {
        static void Main(string[] args)

        {

            string[] lines = System.IO.File.ReadAllLines(@"C:\Users\sp\Documents\Visual Studio 2010\Projects\store1\st1\input_1.txt");
            System.Console.WriteLine(lines);



        }
    }
}

masterinex 0 Newbie Poster · Answer 5 · 2012-03-27T23:17:07+00:00

ok, it seems that C# can only read some lines from the file.

Now I am trying to figure out how to get the first word, from the first line.
for example if my line is rock your body 1233

how can I get the first word rock or the last word 1233 ?

I tried

System.Console.WriteLine(lines[0][0]);

but that will give the first letter from the first word

masterinex 0 Newbie Poster · Answer 6 · 2012-03-28T01:00:58+00:00

I also tried this way. but

for some reason the line s = line.Split(" "); seems not to work

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace s1
{
    class Program
    {
        static void Main(string[] args)

        {

            string[] lines = System.IO.File.ReadAllLines(@"C:\Users\sp\Documents\Visual Studio 2010\Projects\store1\s1\s1.txt");
            System.Console.WriteLine(lines);
            System.Console.WriteLine(lines[0]);
            System.Console.WriteLine(lines[0][0]);

            foreach (string line in lines)
            {

               string s  = " ";
               s = line.Split(" ");
               System.Console.WriteLine(s);
            }





        }
    }
}

Momerath 1,327 Nearly a Senior Poster Featured Poster · Answer 7 · 2012-03-28T01:53:45+00:00

String.Split returns an array, not a single string

foreach (String line in lines) {
    String[] parts = line.Split(' ');
    Console.WriteLine(parts[0]); // first part
}

Momerath 1,327 Nearly a Senior Poster Featured Poster · Answer 8 · 2012-03-28T01:53:47+00:00

String.Split returns an array, not a single string

foreach (String line in lines) {
    String[] parts = line.Split(' ');
    Console.WriteLine(parts[0]); // first part
}

Momerath 1,327 Nearly a Senior Poster Featured Poster · Answer 9 · 2012-03-28T01:54:06+00:00

String.Split returns an array, not a single string

foreach (String line in lines) {
    String[] parts = line.Split(' ');
    Console.WriteLine(parts[0]); // first part
}

Momerath 1,327 Nearly a Senior Poster Featured Poster · Answer 10 · 2012-03-28T01:53:19+00:00

String.Split returns an array, not a single string

foreach (String line in lines) {
    String[] parts = line.Split(' ');
    Console.WriteLine(parts[0]); // first part
}

Momerath 1,327 Nearly a Senior Poster Featured Poster · Answer 11 · 2012-03-28T01:53:32+00:00

String.Split returns an array, not a single string

foreach (String line in lines) {
    String[] parts = line.Split(' ');
    Console.WriteLine(parts[0]); // first part
}

Momerath 1,327 Nearly a Senior Poster Featured Poster · Answer 12 · 2012-03-28T01:53:31+00:00

String.Split returns an array, not a single string

foreach (String line in lines) {
    String[] parts = line.Split(' ');
    Console.WriteLine(parts[0]); // first part
}

Momerath 1,327 Nearly a Senior Poster Featured Poster · Answer 13 · 2012-03-28T01:53:31+00:00

String.Split returns an array, not a single string

foreach (String line in lines) {
    String[] parts = line.Split(' ');
    Console.WriteLine(parts[0]); // first part
}

Momerath 1,327 Nearly a Senior Poster Featured Poster · Answer 14 · 2012-03-28T01:54:02+00:00

String.Split returns an array, not a single string

foreach (String line in lines) {
    String[] parts = line.Split(' ');
    Console.WriteLine(parts[0]); // first part
}

Momerath 1,327 Nearly a Senior Poster Featured Poster · Answer 15 · 2012-03-28T01:53:46+00:00

String.Split returns an array, not a single string

foreach (String line in lines) {
    String[] parts = line.Split(' ');
    Console.WriteLine(parts[0]); // first part
}

how to read a text file and display some lines from it in C# ?

Dani AI

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