Help me understand some code

Patrick Gareau

using System;

using System.Text;

namespace forgetCode{

class Program

{

public static void Main(string[] args)

{

Console.WriteLine("Enter the string to reverse :");

string name = Console.ReadLine();

StringBuilder builder = new StringBuilder();

for (int i = name.Length - 1; i >= 0; i--)

{

builder.Append(name[i]);

}

string newName =builder.ToString();

Console.WriteLine(newName);

}

}}

Can someone please explain how this code reverses a string and why would you use stringbuilder over string?

3 Replies

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Salman Beg7y ago
Accepted answer
Hi. When you enter like "abc" then first it will find out it's length and which is 3. As per your for loop, first I is 2 because you are doing length-1. After that it will check for I not equal to 0. Then it will get index of 2 means which is c. After this it will execute i--. So next loop it will get b and subsequently a and you are adding in StringBuilder. After loop completed it will print cba. To know about StringBuilder and string then you can follow this link, https://www.c-sharpcorner.com/blogs/difference-between-string-and-stringbuilder-in-c-sharp1
Patrick Gareau7y ago
Thank you both that helped me understand the code very well.
Shweta Lodha7y ago
Here stringbuilder is used because value is keep updating. If you will use string type then everytime a new variable will be created in memory whenever you are updating values. Whereas stringbuilder would be a single object in memory, due to append.

How code is working:
This code is taking string value as an input, for example ABC and taking the length of it ( here it is 3). Then code is reading the string from reverse order using index value based on length.