C语言实现字母的大小写转换

//实现字母大小写的转换，
#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
int main()
{
 int ch = ' ';
 int ch1 = 'a' - 'A';
 while (1)
 {
  scanf("%c", &ch);
  if (ch >= 'a'&&ch <= 'z')
  {
   printf("%c\n", ch - ch1);
  }
  else if (ch >= 'A'&&ch <= 'Z')
  {
   printf("%c\n", ch + ch1);
  }
  else if (ch>=1||ch<=2)
  {
   continue;
  }
 }
 system("pause");
 return 0;
}