Inserting user defined number of spaces before and after string using C#

Question

I am using string builder to format my string to append and prepend white spaces at the start and end of the string

here is what I have so far:

private void button1_Click(object sender, EventArgs e)
{
   String Word = textBox1.Text;
   AppendPrependText(Word);
}
private void AppendPrependText (String Word)
{
   int count = Convert.ToInt32(textBox2.Text);
   int WordCount = Word.Count();
   int totalChar = count + WordCount;
   string format = "{-"+totalChar+ "," +totalChar+ "}";
   StringBuilder sb = new StringBuilder();

   sb.AppendLine(string.Format(format, Word));
   textBox3.Text = sb.ToString();
}

but I'm getting the error incorrect format. What am i doing wrong?

Answer 1

I think you need not to use separate operation for formatting the string, you can use .AppendFormat() method of the StringBuilder Class. Here is a sample code for you:

StringBuilder sbAppendFormat = new StringBuilder();
int numberOfSpaces=0;
if(int.TryParse(textBo2.Text, out numberOfSpaces))
{
    string whiteSpaceSequence= new string(' ',numberOfSpaces);
    sbAppendFormat.AppendFormat("{0}{1}{0}", whiteSpaceSequence, "This is your String");
}
textBox3.Text = sbAppendFormat.ToString();

Note:- Assume that you need to add Some white spaces(let it be 5) before and after the specific word.

Answer 2

There's two issues here. The first is that you're correctly using a StringBuilder to format a string which reduces the overhead caused by concatenation but you're also performing extra concatenation on that format local variable.

The second issue is that your format string is wrong: it doesn't include the argument index. Your method expects a single word, so that index should be zero before the padding instruction.

Fortunately, you could skip past the concatenation of the format string and simply append your user-defined space (or whatever character) to the fresh instance of the StringBuilder

Answer 3

Your code has some errors:

Format Exception will be thrown by this line for sure:

sb.AppendLine(string.Format(format, Word));

Your current format doesn't contain any {0} in which the Word value should be replaced.

//you should put here somewhere {0} in the format or remove the Word for string.Format
//for an example
string format = "{-" + totalChar + "," + totalChar + "}{0}";

Also this line is possible Format Exception if the textBox2.Text is for an example a11:

int count = Convert.ToInt32(textBox2.Text);

You need to use int.TryParse

int count = 0;
int.TryParse(textBo2.Text, out count);

Answer 4

What seems to be the issue is

string format = "{-"+totalChar+ "," +totalChar+ "}";

Letz say if totalChar = 10; than

format = "{-10,10}"

which is not a valid format whereas it should be

{0,10}{1,10}

and thus your string would look like

Console.WriteLine(string.Format("{0,10}{1,10}", "Mohit",""));

The third argument was intentionally left blank so that nothing would be printed after the word. but you will have 10 spaces.

But I would recommend you to use String.PadRight and String.PadLeft instead.

An example to demostrate your task using PadLeft and PadRight

int count = 5;
string st = "mohit ";
int WordCount = st.Count();
int totalChar = count + WordCount;

st = st.PadRight(totalChar, ' ');
st = st.PadLeft(totalChar + count, ' ');
Console.WriteLine(st);