否则 如果条件优先于条件?

Question

请原谅这个初学者的问题。我刚刚开始编程，我正在使用 C 作为下面的代码。

此代码的目的是让计算机猜测用户选择的数字。计算机将根据"太低"或"太高"等队列缩小可用数字的范围。

computer_guess(int answer)
{
int lownum, highnum, guess, answer;
//Instructions
printf("Please use 'h' for too high or 'l' for too low ");
printf("for incorrect guess. Use 'c' if the guess is right.n");
guess = (lownum + highnum)/2;
printf("n %d. n", guess);
printf("Is this the right number?");
do
{
answer = getchar();
if (answer == 'h') 
{
guess = (lownum + (highnum -1))/2;
printf("%d n", guess);
}
else if (answer == 'l') //If the computer's guess is too high.
{
guess = ((lownum + 1) + highnum)/2;
printf("%d n", guess);
}
else if (answer != 'n')//If the user enters letters other than 'h' or 'l', an error message will be returned.
{
fflush(stdin);  
printf("Invalid. Please use either h (too high), l (too low) or c (correct).");
}
} while (answer != 'c');
if (answer == 'c')//If the correct answer is given, the game will end.
{
printf("The computer has guessed the right number.");
}
return 0;
}

我遇到的问题是我的代码似乎忽略了我的 while 条件(while (答案 ！= 'c'))。在我的输出中，即使我输入"c"，它也会在最后一个"else if"块中打印 Error 语句和关于正确的语句。

这是输出：

Invalid. Please use either h (too high), l (too low) or c (correct). The computer has guessed the correct answer!

我需要做什么来确保输入"c"时不会打印错误？

谢谢！

Answer 1

程序的语句按照 C 标准预定义的顺序执行。这包括计算do/while循环的while条件。

循环在到达循环主体的末端时检查条件。这包括执行循环内的所有if语句及其else分支。由于您对循环内的'c'没有特殊处理，因此if (answer != 'n')分支将被执行，并提供您看到的打印输出。

您可以通过使用"永久"循环并在其正文中处理'c'输入来解决此问题：

for (;;) {
answer = getchar();
if (answer == 'c')  {
break;
}
... // The rest of your code goes here
}