为什么`if(guess!='a'|| guess!='A'||…)`不起作用？ - java

Improve this question

这是我的代码，我知道if语句真的很长，代码可能会更高效，但是我只是想知道答案，因为它使我发疯。

while (whileloop == 1)
  {
    if (guess != 'a' || guess != 'A' || guess != 'b' || guess != 'B' || guess != 'c' || guess != 'C' || guess != 'd' || guess != 'D' || guess != 'e' || guess != 'E' || guess != 'f' || guess != 'F' || guess != 'g' || guess != 'G' || guess != 'h' || guess != 'H' || guess != 'i' || guess != 'I' || guess != 'j' || guess != 'J' || guess != 'k' || guess != 'K' || guess != 'l' || guess != 'L' || guess != 'm' || guess != 'M' || guess != 'n' || guess != 'N' || guess != 'o' || guess != 'O' ||guess != 'p' || guess != 'P' || guess != 'q' || guess != 'Q' || guess != 'r' || guess != 'R' || guess != 's' || guess != 'S' || guess != 't' || guess != 'T' || guess == ' ')
    {
      System.out.println ("\nNot a Point. Try again.");
      guess = IBIO.inputChar ("If the missile is launched from Point B, which Point will the missile hit? ");
    }
    else 
      whileloop = 2;
  }

参考方案

因为您需要逻辑和&&（而不是逻辑或||）。当您使用||时，如果任何条件为true（例如字母A不为字母B，则整个表达式为true）。您可以将||与两个ands一起使用。就像是

 if (!(guess >= 'a' && guess <= 'z') || !(guess >= 'A' && guess <= 'Z'))

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