此代码错误，需要重写

This code is wrong and need rewrite

if(ch=='a'){
    if(ch=='a'){
        ch='*';
    }
}
putchar(ch);

根据作业，当你遇到'a'时，你知道只有当你知道下一个字母时才该做什么。

你需要一个变量来告诉你是否有'a'等待。

如果'a'被搁置，你需要调整代码来处理。

代码如下：

As per assignment, when you encounter an 'a', you know what to do only when you know the next letter.
You need a variable to tell you if you have an 'a' on hold or not.
And you need to adapt the code to handle if a 'a' is on hold or not.
The code will look like:

if(ch=='a'){
  if (a 'a' is on hold) {
    putchar('*');
    reset number of 'a' in hold
  }
  else {
    add a 'a' in hold
  }
}
else {
  if (a 'a' is on hold) {
    ...
  }
  ...
}

[更新]

[Update]

你可以解释一下你的意思吗？保持和保持英语不是我的第一语言

could you please explain what you mean by "in hold" and "on hold" english is not my first language

样本输入

Sample input

Input   on Hold   Output
  b                 b
  a       a
  n                 a n
  a       a
  a                 *
  a       a
  n                 a n
  a       a
  \n                a \n

您可以将'暂停'翻译为等待下一个输入。换句话说：你不知道怎么处理'a'，直到你知道是否有第二个'a'。

You can translate 'on hold' as waiting for next input. Said otherwise: you don't know what to do with a 'a' until you know if there is a second 'a'.