Here, I am going to present a very compact recursive c# code to compute all the permutations of a given string. Look at the following c# method:

public void PrintPermutations(string stringToPermute, string prefix)
{
   if (stringToPermute.Length <= 0)
   {
       Debug.WriteLine(prefix);
   }
   else
   {
       for(int i=0;i<stringToPermute.Length;i++)
           PrintPermutations(stringToPermute.Replace(stringToPermute[i].ToString(), ""), prefix + stringToPermute[i]);
   }
}

To find all the permutations of the string “ABC”, for example, you will call the method as follows:

PrintPermutations("ABC", ""); Also note that, I assume that stringToPermute parameter is a string containing non-repeating characters.

Often in the batch script we need to change to the directory from where the batch file is executing. Mainly when you are shipping the batch file with your application, you may want to launch some executable from the batch file, for example. So, if you put batch file where the executable is, following batch script will do the job for you:

cd %~dp0
MyApplication.exe

First statement changes current directory to the location of batch file and then second statement launches the application.

Many a time we run into requirement of executing simple SQL scripts using command prompt. Microsoft gives us a utility called “sqlcmd” just for that. Following is a very simple query executed using this tool: sqlcmd -S .\SQLEXPRESS -E -Q "Drop Database SampleDB" Where SampleDB is the database name i want to drop, -S switch specifies the server instance, -E switch specifies that i want to use trusted connection and -Q switch specifies the SQL query i want to execute. This tool is quite powerful and there are several switches that you can use to meet different requirements. You can open command prompt and see help (sqlcmd /?) for all the different switches that it supports.