用函数修改全局变量？

Question

在 mousePressed 中，我需要 aNumber 的值，但我无法传递 mousePressed(int aNumber).. 所以当通过 javascript 调用 theNumbers 时，我需要某种全局变量来保持修改..

int number = 0;
int theNumbers(int aNumber) { //aNumber = 1, 2, or 3, from the javascript)

  println(number); // prints the correct number
  int number = aNumber; // set the global variable number equal to aNumber 
  return number;
}

void mousePressed() {
  aLongNumber = 10000000000;

  println(number); // prints 0 right now, should print the value of aNumber
  long numberLong = aLongNumber + (number * aLongNumber);
}

Answer 1

您在theNumbers() 中声明局部变量，只需在number 之前删除int，这样您的函数就会如下所示：

int theNumbers(int aNumber) { //aNumber = 1, 2, or 3, from the javascript)

  println(number);
  number = aNumber; // removed int that made new local variable "number"
  return number;
}

Answer 2

删除这一行：

 int number = aNumber;

您将参数复制到“数字”变量，然后将其返回。实际上，您正在打印在您发布的任何地方的代码中未更改的全局变量“数字”，然后返回参数，这与您刚刚完成的计算无关。

您可能想修改全局参数number，然后返回它，所以进行更改：

int theNumbers(int aNumber) {
   // calculations for number (based on aNumber? contains number=SOMETHING somewhere?)

   println(number); // prints the correct number    
   return number;
}

编辑：

然后修改全局即可。从int number = aNumber; 中删除类型，这样您就不会重新初始化变量。最后：

int theNumbers(int aNumber) {
   // calculations for number (based on aNumber? contains number=SOMETHING somewhere?)

   println(number); // prints the correct number    
   number = aNumber;
   return number;
}