C语言编程-B1FF过滤器

输出显示结果
Enter message:hello i am guitronic,to c or not to c ,it is a question!

H3LL0 1 4M GU1TR0N1C,T0 C 0R N0T T0 C ,1T 15 4 QU35T10N!!!

#include 
#include 
#include 
int main()
{
    #define N 100
    char ch[N]={0};
    int a=0;
    printf("Enter message:");
    for (int i = 0; i < N; i++) {
        if((ch[i]=getchar())!='n')
        {
            a++;
            if((ch[i]>='a')&&(ch[i]<='z')) ch[i]=toupper(ch[i]); //转大写
        }
        else  break;
    }
    for (int i = 0; i < a; i++) {
      switch(ch[i])
      {
          case 'A': ch[i]='4';break;
          case 'B': ch[i]='8';break;
          case 'E': ch[i]='3';break;
          case 'I': ch[i]='1';break;
          case 'O': ch[i]='0';break;
          case 'S': ch[i]='5';break;
          default:;
      }
      putchar(ch[i]);
    }
    for (int i = 0; i < 10; i++) {
      printf("!");
    }
    
    return 0;
}