how to sort string without using array.sort

Prasanth R

13y26.1kVisual Basic .NET

if suppose i have
Dhoni
Raina
Jadeja
Albie
as my string i have to sort it as
Albie
Dhoni
Jadeja
Raina

5 Replies

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Vulpes13y ago
Accepted answer
Here's a 'naive' approach to sorting strings which only works if (as here) the strings all begin with different letters:

using System;

class Program
{
static void Main()
{
string[] names = {"Dhoni", "Raina","Jadeja", "Albie"};
string[] alpha = new string[26];
foreach(string name in names) alpha[name[0] - 65] = name;
int i = 0;
foreach(string name in alpha)
{
if (name != null)
{
names[i] = name;
i++;
}
}
foreach(string name in names) Console.WriteLine(name);
Console.ReadKey();
}
}

And here's another approach which uses the Gnome sort algorithm (http://en.wikipedia.org/wiki/Gnome_sort):

using System;

class Program
{
static void Main()
{
string[] names = {"Dhoni", "Raina","Jadeja", "Albie"};
GnomeSort(names);
foreach(string name in names) Console.WriteLine(name);
Console.ReadKey();
}

static void GnomeSort(string[] sa)
{
int pos = 1;
while (pos < sa.Length)
{
if (String.Compare(sa[pos], sa[pos-1], StringComparison.OrdinalIgnoreCase) >= 0)
{
pos++;
}
else
{
string temp = sa[pos];
sa[pos] = sa[pos - 1];
sa[pos - 1] = temp;
if (pos > 1) pos--;
}
}
}
}
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Vulpes13y ago
Well, name[0] is the first character of the string name and is going to be one of the letters A to Z.

These letters have ASCII/Unicode values between 65 and 90 inclusive. So, if you subtract 65, you're going to be left with a number between 0 and 25.

The alpha array has 26 elements, one for each letter, so the expression name[0] - 65 will therefore give you the appropriate index into this array.

For example, if you take "Dhoni" the ASCII value of 'D' is 68 and subtracting 65 leaves 3. We therefore set alpha[3] equal to "Dhoni".

The alpha array will therefore end up containing all the names in the correct order and if you remove those elements that are null and assign the other elements back to the names array they will be in sorted order.
0
Prasanth R13y ago
alpha[name[0] - 65] = name; can u explain what this line mean too?? i cant able to understand this line
0
Jeetendra Gund13y ago
Hi,
Prasanth,
Try this,

class Program
{
static void Main(string[] args)
         {
        string[] str = new string[] {"Dhoni", "Raina", "Jadeja", "Albie"};
        int cnt = str.Length - 1;
        for(int i = 0; i < cnt; i++)
                 {
                 for(int j = cnt; j > i; j--)
                         {
                        if(((IComparable)str[j-1]).CompareTo(str[j])>0)
                        {
                                var temp = str[j-1];
                                str[j-1] = str[j];
                                str[j] = temp;
                                }
                         }
                 }
          foreach(var item in str)
        {
                Console.WriteLine(item);
                 }
         }
}
Thanks.
0
Tulasi13y ago
Hi prasanth

With LINQ :

string[] strarray=new string[]
{
"Dhoni",
"Raina",
"Jadeja",
"Albie"
}
var sort=from s in strarray orderby s select s;
foreach (string c in sort)
{
Console.writeLine(c);

}

0