编辑代码

using System;

public class HelloWorld
{
    public static void Main()
    {
        int[] a={1,2,3};
        int many=0;
        foreach(var item in a)
        {
            //Console.WriteLine(item);
            many++;

        }
        int sum=0;
        foreach(var item in a)
        {
            for(int i=0;i<many;i++)
            {
                
                sum=item+a[i];
                    
                
                Console.WriteLine(sum);
            }
        }
        
    }
}