using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using System.Security.Cryptography;

namespace HelloWorld
{
	public class Program
	{
        static string alphaCaps = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        static string alphaLow = "abcdefghijklmnopqrstuvwxyz";
        static string numerics = "1234567890";
        static string special = "@#$-=/";
        string allChars = alphaCaps + alphaLow + numerics + special;
        //Random r = new Random();
        byte[] randomBytes = new byte[60];
            RNGCryptoServiceProvider rngCrypt = new RNGCryptoServiceProvider();
            rngCrypt.GetBytes(randomBytes);
           string r =  Convert.ToBase64String(randomBytes);

        public string GenerateRandomStrongPassword(int length)
        {
            String generatedPassword = "";
            if (length < 4)
                throw new Exception("Number of characters should be greater than 4.");
            int lowerpass, upperpass, numpass, specialchar;
            string posarray = "0123456789";
            if (length < posarray.Length)
            posarray = posarray.Substring(0, length);
            lowerpass = getRandomPosition(ref posarray);
            upperpass = getRandomPosition(ref posarray);
            numpass = getRandomPosition(ref posarray);
            specialchar = getRandomPosition(ref posarray);


            for (int i = 0; i < length; i++)
            {
                if (i == lowerpass)
                    generatedPassword += getRandomChar(alphaCaps);
                else if (i == upperpass)
                    generatedPassword += getRandomChar(alphaLow);
                else if (i == numpass)
                    generatedPassword += getRandomChar(numerics);
                else if (i == specialchar)
                    generatedPassword += getRandomChar(special);
                else
                    generatedPassword += getRandomChar(allChars);
            }
            return generatedPassword;
        }

        private string getRandomChar(string fullString)
        {
            return fullString.ToCharArray()[(int)Math.Floor(r.NextDouble() * fullString.Length)].ToString();
        }

        private int getRandomPosition(ref string posArray)
        {
            int pos;
            string randomChar = posArray.ToCharArray()[(int)Math.Floor(r.NextDouble()* posArray.Length)].ToString();
            pos = int.Parse(randomChar);
            posArray = posArray.Replace(randomChar, "");
            return pos;
        }
		
		public static void Main(string[] args)
		{
			Program p = new Program();
			string rs = p.GenerateRandomStrongPassword(30);
            Console.WriteLine(rs);
		}
	}
}

C Sharp Online Compiler

Write, Run & Share C# code online using OneCompiler's C# online compiler for free. It's one of the robust, feature-rich online compilers for C# language, running on the latest version 8.0. Getting started with the OneCompiler's C# compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C# and start coding.

Read inputs from stdin

OneCompiler's C# online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

using System;
 
namespace Sample
{
  class Test
    {
      public static void Main(string[] args)
       {
         string name;
         name = Console.ReadLine();
         Console.WriteLine("Hello {0} ", name);
	}
     }
}

About C Sharp

C# is a general purpose object-oriented programming language by Microsoft. Though initially it was developed as part of .net but later it was approved by ECMA and ISO standards.

You can use C# to create variety of applications, like web, windows, mobile, console applications and much more using Visual studio.

Syntax help

Data types

Data TypeDescriptionRangesize
intTo store integers-2,147,483,648 to 2,147,483,6474 bytes
doubleto store large floating point numbers with decimalscan store 15 decimal digits8 bytes
floatto store floating point numbers with decimalscan store upto 7 decimal digits4 bytes
charto store single characters-2 bytes
stringto stores text-2 bytes per character
boolto stores either true or false-1 bit

Variables

Syntax

datatype variable-name = value;

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition or set of few conditions IF-ELSE is used.

if(conditional-expression) {
   // code
} 
else {
   // code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression) {    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
...    
    
default:     
 // code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement) {
  // code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition) {
 // code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {
  // code 
} while (condition);

Arrays

Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.

Syntax

data-type[] array-name;

Methods

Method is a set of statements which gets executed only when they are called. Call the method name in the main function to execute the method.

Syntax

static void method-name() 
{
  // code to be executed
}