using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication7
{
    class Program
    {
        static void Main(string[] args)
        {
            char[] a={'a','b','c','d','1','2','3'};
            foreach(char i in a)
            {
                int j;
                for (j= 0; j < 4; j++)
                {
                    a[j] = a[j] - 32;
                  
                }
                for (j = 0; i < 7; j++)
                {
                    Console.WriteLine();
                }
            }
        }
    }
}




新手不知道怎么做这个题目 ，求帮助

没有人么

foreach(char ch in a)
{
    if(ch>='a'&&ch<='z')
    {
        ch-=32;
    }
    Console.Write(ch);
}

还是有错误。。。

string s;
s="123abc";
s=s.ToUpper();

string s1,s2;
            s1 = "123abc";
            s2 = "";
            foreach (char a in s1)
            {
                if ((int)a >= 97 && (int)a <= 122)
                {
                    s2 = s2 + (char)((int)a-32);
                }
                else
                {
                    s2 = s2 + a;
                }
            }
            textBox1.Text = s2;

好久没有用c#了，不知道这样不行