以下哪个代码片段不能正确将字符'5'转换为整数5？

{{ select(1) }}

• char c = '5';
  int num = c - '0';
  

• char c = '5';
  int num = (int)c;
  

• char c = '5';
  int num = c - 48;  // '0'的ASCII码是48