two string array comparison in C# programmatically?string array comparisons?

string[] da=null;

string[] com=new string[50];

//Com stores value

for(int i=0;i<9;i++){

com[i]=i;

i++;

}

for (int i = 0; i < da.Length; i++)
                             {
 
                                 for (int j = 0; j < com.Length; j++)
                                 {
 
                                     if (da[i].ToString().Trim() != com[j].ToString().Trim())
 
                                     {
                                         ListItem itemsoft = new ListItem();
                                         itemsoft.Text = com[j];
                                         itemsoft.Value = com[j];
                                         chksoft.Items.Add(itemsoft);
                                     }
                                 }
                             }