永久更改参数的值 [英] permanently changing value of parameter

问题描述

我有一个功能检查接受一个布尔值作为参数，采用布尔值，然后改变它。我总是向这个函数传递一个全局变量，如：

 检查（4 some_global_boolean，'A'）;
 

和我想要换到的变量保持检查后调用。眼下，这种变化不会超出这个函数调用。我该怎么做呢？

 布尔检查（INT键，布尔prev_key_high，焦炭C）{ 如果（键== LOW）{
    如果（prev_key_high）{
      prev_key_high = FALSE;
      Serial.println（C）;
      返回true;
}
  }  其他{
    prev_key_high = TRUE;
    返回false;
  }
}
 

解决方案

您应该传递指针，但你必须改变所有用途为取消引用指针是这样的：

 布尔检查（INT键，布尔* prev_key_high，焦炭C）{    ...
    如果（* prev_key_high）
    ...
    * prev_key_high = TRUE;
    ...
 

I have a function check that takes a boolean as an argument, uses the value of the boolean and then changes it. I always pass this function a global variable, like:

check(4, some_global_boolean, 'a');

and I want the change to the variable to remain after "check" is called. Right now, the change is not going beyond this function call. How do I do this?

boolean check(int key, boolean prev_key_high, char c){

 if (key == LOW) {
    if ( prev_key_high){
      prev_key_high = false;
      Serial.println(c);
      return true;
}
  }

  else {
    prev_key_high = true;
    return false;
  }
}

解决方案

You should pass the pointer, but you'll have to change all usages to dereferenced pointer like this:

boolean check(int key, boolean *prev_key_high, char c){

    ...
    if (*prev_key_high)
    ...
    *prev_key_high = true;
    ...

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