CODEWITHSUNDEEP
c#.net
NetSurfer
NetSurfer

Reputation: 123

appending string horizontally in c#

I am new to C# and trying a demo program in this program my intended output is:

Id     1 2 3 4 5 6 7 8 9
Roll # 1 2 3 4 5 6 7 8 9

and this is what I have tried :

static void Main(string[] args)
{
    StringBuilder sb = new StringBuilder();
    sb.Append("Id ");
    for (int i = 0; i < 10; i++)
    {
        sb.Append(i+" ");
    }
    sb.AppendLine();
    sb.Append("Roll# ");
    for (int i = 0; i < 10; i++)
    {
        sb.Append(i + " ");
    }
    Console.WriteLine(sb);
}

though it gives me desired output but here I have to iterate through for loop twice. Is there any way by which only iterating once I can get the same output, using some string formatting of C#?

Upvotes: 3

Views: 418

Answers (3)

Cid
Cid

Reputation: 15247

This can be done without explicit looping, using Enumerable.Range to "generate a sequence of integral numbers within a specified range", along with string.Join() to concatenate the previously created range with the string " " :

// using System.Linq;

string range = string.Join(" ", Enumerable.Range(1, 10)); // "1 2 3 4 5 6 7 8 9 10"
sb.AppendLine($"Id {range}");
sb.AppendLine($"Roll# {range}");

If you really want to use a for loop to build your sequence, you can build your own Range method such as :

public static IEnumerable<int> Range(int min, int max)
{
    if (min > max)
    {
        throw new ArgumentException("The min value can't be greater than the max");
    }
    for (int i = min; i <= max; i++)
    {
        yield return i;
    }
}

And then Join like previously :

var range = string.Join(" ", Range(1, 10));
sb.AppendLine($"Id {range}");
sb.AppendLine($"Roll# {range}");

Or build an array/List/whatever collection and then use string.Join() :

var arr = new int [10];
for (int i = 1; i <= 10; i++)
{
    arr[i - 1] = i;
}

string range = string.Join(" ", arr);
sb.AppendLine($"Id {range}");
sb.AppendLine($"Roll# {range}");

Or directly build a string in the loop :

var sbRange = new StringBuilder();
for (int i = 1; i <= 10; i++)
{
    sbRange.Append($"{i} ");
}
// You can use a string and trim it (there is a space in excess at the end)
string range = sbRange.ToString().Trim();

sb.AppendLine($"Id {range}");
sb.AppendLine($"Roll# {range}");

Upvotes: 4

Christopher
Christopher

Reputation: 9804

This will always require at least 3 loops:

  • One for the creation for the array.
  • One for each WriteLine.

At best you can have somebody elses code do the looping for you.

Unless you are interested in pulling stunts like manually inserting the Newline into a really long string, there is no way to save even a single loop. But such a thing is just unreliable and should not be atempted.

It honestly sounds a lot like a Speed Question, and for those we have the speed rant. You should read it either way, but can skip part 1.

The only improovement I can think of is building those strings with a stringbuilder. String concatenation in loops can be a bit troublesome. But on this scale it works either way.

Upvotes: 1

Sach
Sach

Reputation: 10393

Instead of 1, use 2 StringBuilder instances:

StringBuilder sb1 = new StringBuilder();
StringBuilder sb2 = new StringBuilder();
sb1.Append("Id ");
sb2.Append("Roll# ");
for (int i = 0; i < 10; i++)
{
    sb1.Append(i + " ");
    sb2.Append(i + " ");
}
Console.WriteLine(sb1);
Console.WriteLine(sb2);

Upvotes: 1

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