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

Question

这里是我的代码，我知道if语句很长，代码可能会更有效率，但我只是想知道这个答案，因为它会让我疯狂。

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; 
    } 

Answer 1

因为你想要一个合乎逻辑的和&&（不是逻辑或||）。如果任何条件为true（例如字母A不是字母B，整个表达式为真），则使用||。你可以使用带有两个ands的||。类似于

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