How to write text in a specific line without overwriting the current text using C#?

Question

1.00/5 (1 vote)

See more:

I've been trying to write new texts in a specific line without completely overwriting the current contents of the file but I can't seem to make it work. For example, in my file called Test.txt, This is whats currently written in it:

1
2
3
4

8
9
10

As you may have noticed, I did not inlude the numbers 5,6 and 7. There is also a space where you can insert 5,6 and 7. But as i tried inserting those numbers, its giving me this output:

1
2
3
4

8
9
101
2
3
4

5
6
7

It clearly have added a bunch of numbers that I did not want. Code for this is indicated below. Hope you guys can help me on this one.

What I have tried:

C#

namespace TestCode
{
    class Program2
    {
        static void Main()
        {

            var lines = System.IO.File.ReadAllLines(@"C:\Users\User1\Documents\Visual Studio 2015\WebSites\MusicStore\Pages\Test.txt");
            lines[5] = "5";
            lines[6] = "6";
            lines[7] = "7";
            System.IO.File.AppendAllLines(@"C:\Users\User1\Documents\Visual Studio 2015\WebSites\MusicStore\Pages\Test.txt", lines);

            

        }
    }
}

Posted 26-Jan-17 1:58am

Bruno Earth

Updated 26-Jan-17 11:53am

Add a Solution

Comments

[no name] 26-Jan-17 8:08am

"AppendAllLines", what exactly do you think "append" means?

3 solutions

Solution 1

Your problem is AppendAllLines. That method adds whatever you are writing to the end of the file. Use WriteAllLines instead.

Also, your insertion of lines is a replacement. There are a few ways of fixing that. You can
1. Use a list instead of an array, and Insert the lines in the appropriate place.
2. Create a new array with the correct number of rows, and copy the read values into the right places.
3. Set lines[4] = "5" + Environment.NewLine + "6" + Environment.NewLine + "7" + Environment.NewLine

**Note - the indexes of the lines need to be zero based, so they are 1 less than the number you have in the line.

Posted 26-Jan-17 2:09am

Midi_Mick

Updated 26-Jan-17 2:10am

v2

Comments

Afzaal Ahmad Zeeshan 26-Jan-17 8:30am

5ed.

As for the option 1, he can also add the elements to any place and then finally just sort the array. Insertion of each element will take same amount of time.

[no name] 27-Jan-17 8:44am

giving an actual example is much better for me to understand. Sorry im still a beginner in coding.

Solution 3

When you don't understand what your code is doing or why it does what it does, the answer is debugger.
Use the debugger to see what your code is doing. It allow you to execute lines 1 by 1 and to inspect variables as it execute, it is an incredible learning tool.

Debugger - Wikipedia, the free encyclopedia[^]
Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]

The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't find bugs, it just help you to. When the code don't do what is expected, you are close to a bug.

Posted 26-Jan-17 11:53am

Patrice T

Comments

[no name] 27-Jan-17 8:45am

thanks for the advice.

Add a Solution

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Afzaal Ahmad Zeeshan · Accepted Answer · 2017-01-26T02:28:00

As already mentioned by NotPoliticallyCorrect in the comment to your question, the AppendAllLines will only append the list to your current data. Nothing more, nothing less.

In order to add 5,6,7 (to the current data and only applicable to this scenario), you also need to later sort the data. That sorting of the data will arrange the lines accordingly.

C#

// read the data
var lines = File.ReadAllLines("path");
var _lines = new List<string>(lines); // string[] to List<string>

_lines.Add("5");
_lines.Add("6");
_lines.Add("7");
lines = _lines.ToArray(); // Come back.

// sort
Array.Sort(lines);

// Write the data
File.WriteAllLines("path", lines);

That will write the data in sequence. You can consider using LINQ here as well, that will give a better readability for the code, but that would require a bit more tinkering to get the code to work.

One more thing, since the data is of string type, the sorting will be like, "1, 10, 2..." and not like, "1, 2,... 10", to use the later one you need to cast the data to integer and then sort it. For that you should look at, Convert.ToInt32() method and use that to convert the list to integers before sorting it.

For an example, please have a look here, Home | .NET Fiddle[^]

How to write text in a specific line without overwriting the current text using C#?

3 solutions

Solution 1

Solution 2

Solution 3

Add your solution here

Preview 0

How to write text in a specific line without overwriting the current text using C#?

3 solutions

Solution 1

Solution 2

Solution 3

Add your solution here

Preview 0

Existing Members

...or Join us