从C ++中的函数返回指向数组的指针？ [英] Return a pointer to array from a function in C++?

问题描述

我是一个开始的程序员，我有一个关于函数的问题，它返回一个指向C ++中double类型的指针。该函数接受两个数组，并将每个元素相加，如向量总和。

I am a beginning programmer and I have a question about a function that returns a pointer to array of doubles in C++. The function takes two arrays and adds up each element, like in a sum of vectors.

我认为正确的方法是......

I think the correct way to do is....

double *myfunction(double *x, double *y, int n){
  double *r = new double[n];
  for(int i=0;i<n;i++){
    r[i] = x[i]+y[i];
  }
  return r;
}

问题是我在主循环中使用该函数像这样的函数

The problem is that I use that function in a while-loop in the main function like this

int main(){
  double *x, *y, *s;
  x = new double[2];
  y = new double[2];
  x = {1,1};
  y = {2,2};

  while(/*some condition */){
    /*some process...*/

    s = myfunction(x,y, 2);

    /*some process...*/
  }

  delete[] x;
  delete[] y;
  delete[] s;
}

我的问题是如何处理内存泄漏？每次我使用myfunction（在while循环中）时，我为变量s保留内存，这意味着如果while循环执行5次，那么程序为变量s保留5倍的内存？

My question is what about the memory leak? Each time I use "myfunction" (inside the while-loop) I reserve memory for the variable "s", that means that if the while-loop is executed 5 times, then the program reserves 5 times the memory for the variable "s"?

有没有办法做到这一点（从函数返回指向数组的指针并在循环中使用该函数）??

Is there exists a way to do this (return a pointer to arrays from a function and use that function inside a loop)??

先进的感谢。

推荐答案

我会说更正确的方式来写 myfunction 是：

I'd say the more correct way to write myfunction is:

std::vector<double> myfunction(double *x, double *y, int n){
  std::vector<double> r;
  r.reserve(n);
  for(int i=0;i<n;i++){
    r.push_back(x[i]+y[i]);
  }
  return r;
}

这样，您不必担心内存泄漏，而您while循环可以是：

That way, you don't have to worry about memory leaks, and your while loop can just be:

while (/* some condition*/) {
    std::vector<double> s = myfunction(x, y, 2);
    // whatever
}

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