Attempting to split a string every space, not getting expected answer

Question

So I actually have most of the code thought up myself and got it working last week, but just now I accidentally deleted it so here I am re-writing! The logic goes, I have a TIN number for input, I want to split this every 3rd digit to neatly fit a physical form I have prepared. To do this, I iterate through the input, modulus by 3, place my delimiter a space, then split it by the delimiter.

So, the following 1234567891012 becomes 123 456 789 1012.

string input = txtTIN.Text;
string digit1 = "0";
string digit2 = "0";
string digit3 = "0";
string digit4 = "0";
StringBuilder sb = new StringBuilder();
for (int i = 1; i < input.Length; i++)
{
    if (i%3 == 0)
    {
        sb.Append(' ');
        sb.Append(input[i]);
    }
}
string formatted = sb.ToString();
Console.WriteLine(formatted);
string[] formatCollection = formatted.Split(' ');
digit1 = formatCollection[0];
digit2 = formatCollection[1];
digit3 = formatCollection[2];
digit4 = formatCollection[3];

I realize now that I post it here that there seems to be something wrong with the string building, as a Console write is returning 1 4 7 out of the input. Not a desired result, but if I remember correctly, all of the pieces are already in place.

(Note, I do not want to use Linq, Regex, or Lists even though I know they are better alternatives. I thought this one up myself and want to see it work in the end.)

Also, how do I make it so that an input of 123456789101251 becomes 123 456 789 101251, in other words, i do not want to split any further than the first 3, something my current code fails to do.

Answer 1

If you really don't want to use LINQ, i would propose to modify your algorithm this way:

StringBuilder sb = new StringBuilder();
StringBuilder partBuilder = new StringBuilder(); 
int partsSplitted = 0;
for (int i = 1; i <= input.Length; i++)
{
    partBuilder.Append(input[i-1]);
    if (i % 3 == 0 && partsSplitted<=3)
    {
        sb.Append(' ');
        sb.Append(partBuilder.ToString());
        partBuilder = new StringBuilder();
        partsSplitted++;
    }
}
sb.Append(partBuilder.ToString());
string formatted = sb.ToString().TrimStart();

With output:

123 456 789 101251

The changed to your idea are minimal and entire loop is the same. Please notify: your for loop should go till i <= input.Length not i < input.Length because you are starting with index 1, not 0.

Could downvoters explain what is wrong with accepted answer?

Answer 2

The code to add the digits int he string is in the wrong place. You are only adding the number to the string if it is index mod 3 is 0

for (int i = 1; i < input.Length; i++)
{

    sb.Append(input[i]);
    if (i%3 == 0)
    {
        sb.Append(' ');            
    }
}

Answer 3

int size = 3;  //size of the chunk
int count = 3; //how many sized chunks will be splitted

int length = input.Length / size;
int iterate = length < count ? length : count;
int tailLength = input.Length - iterate * size;

for (int i = 0; i < iterate; i++)
{
    sb.Append(input.Substring(i, size));
    sb.Append(' ');
}

if (tailLength > 0)
{
    sb.Append(input.Substring(size * iterate, tailLength));
}

Answer 4

There are couple of issues with your code

1. You start your iteration with 1, not 0.
2. You add a space at the beginning of your result.
3. You are only adding the first characters of each group.
4. You don't stop grouping even when your max amount of groups is reached.

This would address your issues:

const int GROUP_LENGTH = 3;
const int GROUP_COUNT = 3;
const int MAX_GROUPED_LENGTH = GROUP_LENGTH * GROUP_COUNT;
int groupedLength = Math.Min(input.Length, MAX_GROUPED_LENGTH);
for (int i = 0; i < groupedLength; i++)
{
    if ((i > 0) && ((i % GROUP_LENGTH) == 0))
    {
        sb.Append(' ');
    }
    sb.Append(input[i]);
}
if (input.Length > MAX_GROUPED_LENGTH)
{
    sb.Append(' ');
    sb.Append(input, MAX_GROUPED_LENGTH, input.Length - MAX_GROUPED_LENGTH);
}

Answer 5

string[] result = new string[4];

int groups = input.Length / 3;
if (groups > 3) groups = 3;

int group;
for (group = 0; group < groups; group++)
{
    result[group] = input.Substring(group*3, 3);
}

// Assert: group < 4
result[group] = input.Substring(group*3);

// Assert: answers in result[0..groupCount-1]
int groupCount = group+1;