如果要计数，只需 Count()借助 Linq 即可；要测试字符串是否相等，请使用 String.Equals :

If you want to count, just Count() with a help of Linq; to test if strings are equal use String.Equals:

System.Linq;
...
// do not do Trim() repeatedly
String testValue = myInput.Trim();

int count = myList
  .Count(item => String.Equals(item.Trim(), 
                               testValue,
                               StringComparison.OrdinalIgnoreCase));