How to print number sequence in reverse order?

Question

1.00/5 (2 votes)

See more:

hi.. i want to print 5 digit number in reverse order..

ex.. 49999,49998,49997,49996.....so on

one more think number of print depend on user input
i.e if user input 3 then it display only 3 print as 49999,49998,49997

any idea?....thanks in advance...

What I have tried:

C#

for(int i =50000; i >=printCopies; i--)
{
   reslt += i.ToString("00000") + System.Environment.NewLine;
}

Posted 14-Jul-20 9:58am

Sam_gaik

Updated 14-Jul-20 23:12pm

v2

Add a Solution

Comments

Patrice T 14-Jul-20 16:41pm

What is the problem with your code?

Sam_gaik 14-Jul-20 17:01pm

It does not work as expected..

Patrice T 14-Jul-20 17:12pm

Elaborate.

3 solutions

Solution 2

That looks to be on the right track.

My only question/recommendation from what you have shown is in regards to reslt :
It should NOT be a String variable, because it is immutable. If this is the case; you should be replacing it with a StringBuilder, which is designed for this.

C#

StringBuilder sbResult = new StringBuilder();

for(int i =50000; i >=printCopies; i--)
{
	sbResult.AppendLine( i.ToString("00000") );
}

reslt = sbResult.ToString();

References:
MS Docs: Strings - C# Programming Guide[^]
MS Docs: StringBuilder Class (System.Text)[^]

Posted 14-Jul-20 10:15am

MadMyche

Solution 3

Am I missing something here? Do you just want to print a line of comma separated decreasing values like this:

C#

 int copies = 3;
 int initialValue = 5000;
 string separator = string.Empty;
 for (int i=0;i <copies;i++)
 {
     Console.Write(separator);
     Console.Write(initialValue - i);
     if (separator.Length==0) separator = ",";
 }
Console.WriteLine();

If you want an IEnumerable so that you can use Linq to select the output. Try this

C#

  IEnumerable <int > numbers = Enumerable.Range(initialValue-copies+1, copies).Reverse();
  IEnumerable <string > numberStrings = Enumerable.Range(initialValue , copies).Select((x,i) = > (x-(i*2)).ToString());
 //print  one number per line
           foreach (int num in numbers)
            {
                Console.WriteLine(num);
            }
//use IEnumerable <string > to join the strings together to give a comma separated string value
            Console.WriteLine(string.Join(',', numberStrings));

Posted 14-Jul-20 23:12pm

George Swan

Comments

Sam_gaik 15-Jul-20 12:00pm

Thanks for your suggestion... !

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2020-07-14T10:10:00

Solution 1

Easiest way to understand is like this:

C#

StringBuilder sb = new StringBuilder();
for (int i = 0; i < userInputLimit; i++)
   {
   sb.AppendLine((50000 - i).ToString());
   }
string result = sb.ToString();

Using a StringBuilder is better than concatenating strings as it "expands" automatically instead of creating a new string every time you add a new bit to the old one.

Posted 14-Jul-20 10:10am

OriginalGriff

Comments

Sam_gaik 15-Jul-20 1:53am

It works...thnks

OriginalGriff 15-Jul-20 2:04am

You're welcome!