从文本文件填充TextBox

Question

Im trying to get specific lines from a file and put them in a another string or maybe if we can put it in anothe textbox it wont be a prob :P

string[] msglines;

msglines = System.IO.File.ReadAllLines(@"C:\\Users\xA\Desktop\MESSAGES.txt");

for (int x = 0; x < msglines.Length; x++)
{
    this.textBox5.Text = msglines[c];
    c = c + 2;
}

I get a : Index was outside the bounds of the array.

Answer 1

If you want to get every second line.

Change your loop to

//Odd Lines
for (int x = 0; x < msglines.Length; x = x + 2)
{
    this.textBox5.Text += msglines[x];
}

//Even Lines
for (int x = 1; x < msglines.Length; x = x + 2)
{
    this.textBox5.Text += msglines[x];
}

As was pointed out in the comments, you can shorten x = x + 2 to x += 2

And in the interest of LinqY Goodness...

//ODDS
msgLines
    .Where((str, index) => index % 2 == 0)
    .ToList()
    .ForEach(str => textBox1.Text += String.Format("{0}\r\n", str));

//EVENS
msgLines
    .Where((str, index) => index % 2 == 1)
    .ToList()
    .ForEach(str => textBox1.Text += String.Format("{0}\r\n", str));

Answer 2

您的循环由x控制，但您通过c进行索引[因此，您需要逻辑来防止c变得大于数组的大小]

Answer 3

Because you are increasing the line index ( c ) by 2 each time; just use x :

this.textBox5.Text = msglines[x];

Of course, from a loop this will result in just the last line being shown. What line is it you actually want to show?

---

Edit re comment; in which case, simply:

StringBuilder sb = new StringBuilder();
for (int x = 1; x < msglines.Length; x+=2)
{
    sb.AppendLine(msglines[x]);
}
this.textBox5.Text = sb.ToString();

Answer 4

In your for loop, you are using c. You need to use x. Could I suggest that you have a look at the reference for for .

Try this instead...

string[] msglines;

msglines = System.IO.File.ReadAllLines(@"C:\\Users\xA\Desktop\MESSAGES.txt");


for (int x = 0; x < msglines.Length; x++)
{
    this.textBox5.Text = msglines[x];                       
}

Answer 5

然后，您应该使用X作为索引，步长为2，而不是1。

Answer 6

For simplicity I'll use an example of taking every other character from a string, but the case of taking every other line from an array of strings is analogous.

Lets take "Hello" as an example for your msglines string

_{(source: javabat.com )}

and let us say that your global variable ci initialized to 0 before you enter the for loop. Your msglines.Lenght will be 5. In the the fourth iteration through the loop (x == 3) you are going to try to access msglines[6], which is outside of the bounds of the array, hence the error.

You probably wanted something along the lines of

int x = 0;
while(x <= msglines.Lenght){
  this.textBox5.Text += msglines[x];
  x = x + 2;
}

or

for(x=0; x <= msglines.Lenght ; x+=2){
  this.textBox5.Text += msglines[x];
}

To get the odd lines you would start with x initialized to 1.

As for which of the two fully equivalent versions above to use, I would suggest using the one that is more readable to you. In my experience that is always the better choice.

Answer 7

Try this

string[] msglines;

 msglines = System.IO.File.ReadAllLines(@"C:\Users\xA\Desktop\MESSAGES.txt");

 for (int x = 0; x < msglines.Length; x++)
  {

      this.textBox5.Text = msglines[x++];

  }                   

Answer 8

You say you want all odd-numbered lines in the TextBox, but your loop will only show the last line, as you overwrite the contents on each pass.

To show all odd-numbered lines, separated by line breaks:

string lineSep = "";
for (int x = 0; x < msglines.Length; x += 2)
{
    this.textBox5.Text += lineSep + msglines[x];
    lineSep = "\r\n";
}

Answer 9

You need to loop the array with Length -1. Array of 45 Length will only index to 44.

Answer 10

You have a double backslash in the ReadAllLines() call, causing it to fail opening the file.

Also, you are using c as an array index, it looks like you want x

Answer 11

The code i wrote is exactly how I want it to be.....

I actually want every odd line from my file to be sent to the textbox.and yeah PS C initializes from 1

Answer 12

Besides the already mentioned indexing problems of c versus x , you are also overwriting textBox5.Text on every iteration, so you'll only ever see the last line. It seems somehow unlikely to be intended behaviour. You might want something like this instead:

this.textBox5.Text += msglines[x]; // note x instead of c

Or if you really want everything and the +2 was a typo in itself you could do this without any loop:

this.textBox5.Text = String.Join( "\n", msglines );

Answer 13

The following function will return an IEnumerable that gives the odd numbered lines in a file:

private IEnumerable<string> GetOddLines(string fileName)
{
    string[] lines = File.ReadAllLines(fileName);
    IEnumerator allLines = lines.GetEnumerator();
    while (allLines.MoveNext())
    {
        yield return (string)allLines.Current;
        if (!allLines.MoveNext())
        {
            break;
        }
    }
}

If you want the even numbered lines, just add a call to allLines.MoveNext() before the while loop.