C# Sharp Exercises: Check whether a number can be express as sum of two prime numbers

C# Sharp For Loop: Exercise-56 with Solution

Write a program in C# Sharp to check whether a number can be express as sum of two prime numbers.

Sample Solution:-

C# Sharp Code:

using System;  
public class Exercise56
{  
    public static void Main()
{
    int n, i, flg1=1,flg2=1,flg3=0,j;
	
	Console.Write("\n\n");
    Console.Write("Check whether a number can be express as sum of two prime numbers:\n");
    Console.Write("-------------------------------------------------------------------");
    Console.Write("\n\n");	


    Console.Write("Input  a positive integer: ");
    n = Convert.ToInt32(Console.ReadLine());	
   for(i=3; i<=n/2; i++)
     {     
/*---------- check for prime---------------*/
      flg1=1;
      flg2=1;
      for(j=2; j<i; j++)
       {     
         if(i%j==0)
           { flg1=0;j=i;}
        }
      for(j=2; j<n-i; j++)
       {     
         if((n-i)%j==0)
           { flg2=0;j=n-i;}
        }
         if(flg1==1 && flg2==1)
           { Console.Write("{0} =  {1} + {2}  \n",n,i,n-i); 
           flg3=1;}
    }
         if(flg3==0)
           {Console.Write("\n{0} can not be expressed as sum of two prime numbers.\n\n",n);}    
}
}

Sample Output:

Check whether a number can be express as sum of two prime numbers:                                          
-------------------------------------------------------------------                                                                                            
Input  a positive integer: 50                                                                               
50 =  3 + 47                                                                                                
50 =  7 + 43                                                                                                
50 =  13 + 37                                                                                               
50 =  19 + 31 

Flowchart:

C# Sharp Code Editor:

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